The Atlas of The Human Embryo - A Scanning Electron Microscopic Atlas
The Atlas of The Human Embryo - A Scanning Electron Microscopic Atlas
The Atlas of The Human Embryo - A Scanning Electron Microscopic Atlas
Dedicated to the memory of the great anatomists and embryologists Wilhelm His (18311904) and Erich Blechschmidt (19041992)
Gerd Steding
Basel Freiburg Paris London New York Bangalore Bangkok Shanghai Singapore Tokyo Sydney
Dr. med. Gerd Steding Former Professor of Anatomy and Head of the Department of Embryology Centre of Anatomy University of Gttingen Germany
Library of Congress Cataloging-in-Publication Data Steding, Gerd. The anatomy of the human embryo : a scanning electron-microscopic atlas / Gerd Steding. p. ; cm. Includes bibliographical references. ISBN 978-3-8055-8361-9 (hard cover : alk. paper) 1. Embryology, Human--Atlases. 2. Scanning electron microscopy--Atlases. I. Title. [DNLM: 1. Embryo, Mammalian--anatomy & histology--Atlases. 2. Microscopy, Electron, Scanning--Atlases. QS 617 S812t 2008] QM602.S738 2008 612.640222--dc22 2008026596
All rights reserved. No part of this publication may be translated into other languages, reproduced or utilized in any form or by any means electronic or mechanical, including photocopying, recording, microcopying, or by any information storage and retrieval system, without permission in writing from the publisher. Copyright 2008 by S. Karger AG, P.O. Box, CH4009 Basel (Switzerland) www.karger.com Printed in Switzerland on acid-free and non-aging paper (ISO 9706) by Reinhardt Druck, Basel ISBN 9783805583619
Contents
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1. 1.1 1.2 1.3 1.4 1.5 1.6 2. 2.1 2.2 2.3 2.4 2.5 2.6 3. 3.1 3.2 4. 4.1 4.2 4.3 4.4 4.5 4.6 5. 5.15.4 5.5 5.6 6. 6.1 6.2 6.3 6.4 VII XIII
External Aspects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 The External Form of the Embryo . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 The Development of the Face . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 The Development of the Pharyngeal Arches . . . . . . . . . . . . . . . . . . . 38 The Development of the Upper Limb . . . . . . . . . . . . . . . . . . . . . . . . . 66 The Development of the Lower Limb . . . . . . . . . . . . . . . . . . . . . . . . . 88 The Development of the External Genitalia . . . . . . . . . . . . . . . . . . . . 108 Endodermal Organs in the Head and Neck . . . . . . . . . . . . . . . . . The Development of the Walls of the Oral Cavity . . . . . . . . . . . . . . The Development of the Nose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . The Development of the Palate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . The Development of the Pharynx . . . . . . . . . . . . . . . . . . . . . . . . . . . . . The Development of the Larynx . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . The Position of the Thymus and the Parathyroid Gland . . . . . . . . 123 124 146 166 178 188 196
Organs in the Thorax . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203 The Development of the Heart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 204 The Development of the Lungs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 254 Organs in the Abdomen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . The Development of the Small Intestine . . . . . . . . . . . . . . . . . . . . . . . The Development of the Liver . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . The Great Vessels of the Trunk . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . The Development of the Stomach . . . . . . . . . . . . . . . . . . . . . . . . . . . . The Origin of the Spleen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . The Development of the Pancreas . . . . . . . . . . . . . . . . . . . . . . . . . . . . Urogenital Organs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . The Development of the Urinary Organs . . . . . . . . . . . . . . . . . . . . . . The Development of the Gonads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . The Reproductive Pathways . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Brain and Sensory Organs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . The Development of the Brain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . The Development of the Eye . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . The Middle and the Internal Ear . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . The Spinal Cord . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 285 286 298 318 332 348 356 369 370 406 412 421 422 468 486 500
VI
Introduction
In this atlas, the forms of the major human organs during the early weeks of prenatal development are depicted. Illustrations of the external form of human embryos have been published in great numbers and are to be found in numerous textbooks dealing with human embryology. However, we predominantly nd a description of organ development with pictures of two-dimensional histological sections or with more or less schematic drawings often made according to historical originals. It is not rare to nd in textbooks, even today, pictures of animal embryos as material for human development. Since it has been shown that results for animal embryos cannot always be simply and uncritically applied to human development, in this atlas of human embryology, only original images of the major organs of human embryos during the rst few weeks of prenatal development are shown. For technical reasons, modern developmental biology is almost exclusively concerned with animal embryos. However, it would be somewhat irresponsible to expect that the use of these new procedures could replace the investigation of human embryos with the traditional tools for the description of form. Sometimes, however, it seems that nowadays only molecular biological techniques and methods of developmental biology are considered to be a suitable approach to understanding developmental processes, whereas the classical morphological methods and procedures are increasingly seen as historical and, thereby, as hardly capable of producing good results. Regrettably, with this approach, it is often ignored that reports on the biochemical processes taking place during development can hardly provide a hint as to the ways and means in which they inuence form. The fact that the steps taking place at the molecular level during the development of a leg of a mouse or chicken are to a large extent similar, however, oers no explanation as to how the nal results of these processes are so dierent in form. To establish under what circumstances and conditions the arm, for example, of a human being is given its characteristic form, rst precise knowledge of the course of development
VII
is necessary. We need to know which steps are involved, from the development of the anlage to the formation of the nished human form. Only when the course of each individual step in these external changes in form has been understood, can there be a chance of also estimating the molecular incidents in the stages of the development of form. Therefore, even nowadays, the classical observation, description and analysis of form, its development and change cannot be ignored altogether, neither within the framework of developmental biological nor embryological medical investigations. In this atlas, all that is depicted are those changes in position and form of the organs, which are visible during embryonic development. It is obvious that, together with these visible changes, a succession of processes in submicroscopic molecular dimensions, which are not directly visible, take place. There has been much conjecture as to the relationship, so to speak, between macroscopic and submicroscopic processes and much has been alleged or even postulated without there having been any success in disproving any one of the hypotheses. Therefore, I restrict myself solely to illustrating phenomena of human organ development which are directly visible and I will keep my views on theories and hypotheses to myself. The readers concept of human organ development will, on the basis of our specimens, hopefully become more vivid and plastic. Just as in the anatomical dissection course the organs concealed under the skin are exposed and become visible by dissection, layer for layer, the organs of an embryo can also be exposed and, thereby, made visible in their position and spatial form. As in an anatomical atlas the position and form of human organs are shown, in this atlas the changes in position and form of some of the human organs during prenatal development are seen in photographs of the specimens. For the selection of the photographs, I made sure that the developmental stages were as close together as possible to make the changes in shapes of the organs clear and comprehensible. To demonstrate the relationships in form and position more reliably than the standard aspects are able to do, images of the same organs photographed from dierent directions are shown. This cannot, of course, be equally successful for every organ, sim-
VIII
ply because the small size of some objects sometimes makes unexpectedly high demands on the patience and dexterity of the author. It would hardly be surprising if some of the photographs shown here might appear peculiar and strange to the experienced observer of histological and schematic illustrations in textbooks. This could be due to the fact that these specimens also do not appear to be as simple and familiar as the two-dimensional sections and repeatedly drawn schemata so often seen. As in everyday life, also in prenatal development, it is often the inconspicuous events which are most important. Temporally close stages may sometimes appear hardly distinguishable from each other and only upon more exact inspection can a characteristic developmental step be recognized. Even if it is customary to speak of the human embryo, it must be remembered that, already in his prenatal life, the human being is a unique and unmistakable individual. As far as possible, I have also tried to keep this aspect of the individual development of form in mind. Since the growth of the embryo is precisely in the early weeks a fundamental factor in the development of form, the pictures of all stages of an organ are, in general, shown at the same magnication. The introductory text to each chapter hardly oers experts anything new. It cannot and should not replace a textbook, but rather explains, only briey, some of the most signicant developmental steps documented in the illustrations. To instruct or teach the readers is not the aim of this atlas, rather it simply oers them an opportunity to develop a more precise conception of the anatomy of the human embryo through the power of their own observations. In this context, I must accept the fact that the choice of photographs and their number cannot satisfy every reader in equal measure and that unnecessary or even absent aspects may be criticized. However, I have endeavoured to give not only human embryologists but also readers on the periphery of human embryology and interested physicians and also laymen an opportunity to make their own observations. As expected from an atlas, the pictures of the specimens are what is most important. Some of these pictures oer an unusual aspect and often also only one small detail from a region. In order
IX
to make orientation in the pictures easier for those who are strangers to human embryology, some explanatory terms have been added in small frames with deliberately simple and small line drawings. These should not distract the reader from looking at the photographs and cannot replace the photographs. In a few large format photographs, abbreviations refer to important terms. To avoid burying the photographs beneath nomenclature, only those illustrations in a chapter have been labelled whose items are not self-explanatory from the previous gure. The nomenclature is oriented on the anatomy of adults as far as possible and on everyday speech and only when unavoidable have technical terms been employed.
Materials and Procedures The embryos shown here were collected and dissected over a period of more than 25 years. I am very grateful to many colleagues, among them friends in many parts of the world, for their willingness to provide me with their material. Human beings are not sacriced especially for the procurement of cadavers for anatomical dissection courses and, for the same reasons, human embryos are neither killed nor bred for the sake of investigation in the eld of human embryology. All of the embryos, without exception, were obtained from legal or medically indicated abortions and were all exclusively employed for the investigations described here. For these reasons, the early stages of human development are not depicted since only embryos of at least 4 weeks of age are available. Following the employment of various techniques, the embryos were xed in glutaraldehyde or paraformaldehyde, partly postxed in Bouins solution, then dehydrated in an ascending alcohol series and dried with CO2 using the critical point method. The embryos were mounted on a specimen support and were cool-sputtered with gold or gold-palladium to a thickness of 30 nm. When the surface layers of a specimen had been photographically documented with the scanning electron microscope (Zeiss Novascan or DSM 960 Zeiss), the deeper layers were exposed with the help of specially made microinstruments, the specimens resputtered and re-photographed with the scanning electron mi-
croscope. Dependent on the region under investigation, up to ten layers were exposed and photographed for each embryo.
Age Determination It is usually not possible to determine the exact developmental age of an embryo because the time point of fertilization of the egg remains unknown. However, estimation of age based on measurements of the greatest length of the embryo or the crownrump length was attempted. Since, however, embryos shrink by up to 20% as a result of xation and the following dehydration dependent upon the techniques employed and, moreover, the extent of shrinkage is dependent on the length of time spent in the various solutions and, of course, just as for adults, there are shorter and taller human embryos, the evaluation of the length cannot be a highly reliable technique for the evaluation of the age. Streeters classication of embryos1 using his term, developmental horizons, was modied by ORahilly and Mller2 who used the term, developmental stages. The disadvantage of this system for the classication into stages is that for the rst 8 embryonic weeks only 23 stages are suggested. Due to the low number of stages in this system, the single stages are not characterized by typical developmental states of all organs, only reached at this stage, but include quite a lot of dierent maturation states of the organs. Since not all organ systems develop concurrently, but rather, for example, the heart can be somewhat further developed than the stomach, the use of developmental stages seems impractical. Therefore, only approximate age estimations are given in weeks, estimated from an assumed time point of fertilization of the egg. The classication of the embryo according to developmental weeks is made on the basis of a comparison of the devel-
1 Streeter GL: Developmental Horizons in Human Embryos. Carnegie Inst Wash Publ Contrib Embryol 1942;30:211245; 1945;31:2763; 1948;32:133203; 1949;33:149167; 1951;34:165196. 2 ORahilly R, Mller F: Developmental Stages in Human Embryos, Including a Revision of Streeters Horizons and a Survey of the Carnegie Collection. Washington, Carnegie Institution of Washington, 1987, Publ No 637.
XI
opmental state of as many embryonic organs as possible with embryos of tolerably exact developmental ages described in the literature. Since, in obstetrics, for the determination of the age of the embryo the rst day of the last period is taken to be the beginning of the pregnancy, the gynaecological age is approximately 2 weeks more than the embryological age given here.
XII
Acknowledgements
I am very grateful to all the co-workers of my old department for their work in collecting and preparing the material for this atlas. In particular, Hans-Georg Sydow deserves respect and thanks for his untiring and conscientious eorts in collecting and preparing the samples for the scanning electron microscopy and his unique dexterity in the dicult job of making the microinstruments for the dissection. I am also very grateful for his invaluable help in the solution of dicult technical problems with the scanning electron microscope. Furthermore, in completing the scanning of the negatives, his work proved to be excellent and of inestimable value. I would also like to thank Kirsten Falk-Stietenroth for her photographic work in the darkroom which she carried out with unsurpassed conscientiousness, great commitment and unique aesthetic competence. I would like to express my gratitude to Anja Aue for taking on the building up of the archives of the specimens and the photographs with great thoroughness, thus making an important contribution to the maintenance of order. I am also grateful to Cyrilla Maelicke for translating the text. And, nally, I would like to thank Dr. Jrg Mnner who as acting head of my old department generously made it possible for me to complete this atlas in my old familiar setting after my retirement. Also following the restructuring of the departments, I was able to continue my work calmly and without interruption in the Centre of Anatomy, for which I expressly thank Dr. Viebahn. Finally, I am highly indebted to the head of the publishing house and all members of sta for their meticulous reproduction of the substantial number of illustrations and the outstanding design of the atlas.
XIII
XIV
External Aspects
1. External Aspects
1.1
20:1
Week 4
1.1.01 Embryo at the beginning of week 4. The amnion has been removed.
cle ity
1.1.02 1.1.011.1.13 Development of the external form of the embryo. Lateral views.
dy wall Sac
Week 5
1.1.03
Embryo at week 5.
Pha l stalk
20:1
Week 5
1.1.04 Embryos at week 5.
1.1.05
Collaps ium d
10:1
Week 5
1.1.05a Same embryo as in gure 1.1.05.
Liv Lo yg g
Week 6
1.1.07
Embryos at week 6.
1.1.08
phalon H U L
10:1
Week 6
phalon
1.1.09
Embryo at week 6.
Hea
1.1.10
Mounting device
1.1.11
phalon
Mo
Lower limb
10
11
5:1
Week 6
1.1.11a Same embryo as in gure 1.1.11.
Week 7
He ons of phalon U
1.1.12
L L
Week 8
1.1.13
Embryo at week 8.
12
13
1. External Aspects
14
1.2
15
60:1
Week 4
1.2.01 Embryos at week 4.
1.2.02
1.2.03
Regio
nce
16
17
30:1
Week 4
1.2.03a Same embryo as in gure 1.2.03.
Week 5
1.2.04
Embryos at week 5.
1.2.05
hI Out
18
19
30:1
Week 5
1.2.06 Embryos at week 5.
Med
ce
nd III
20
21
15:1
Week 5
1.2.07a Same embryo as in gure 1.2.07.
Week 5 / 6
1.2.011.2.17 Developmental stages of the face. Ventral view.
1.2.08
Week 6
1.2.09
Embryos at week 6.
M Phar
ence
1.2.10
22
23
15:1
Week 6
1.2.11 Embryos at week 6.
ences
Week 7
1.2.011.2.17 Developmental stages of the face. Ventral view.
Phar Re
1.2.12
Embryos at week 7.
ences
1.2.13
1.2.14
24
25
15:1
Week 7
1.2.15 Embryo at week 7.
1. External Aspects
ences
Reg
Week 8
1.2.16
Embryos at week 8.
1.2.17
26
27
30:1
Week 4
rch I Rig
1.2.18
Embryo at week 4.
Cut
Week 5
1.2.19
Embryos at week 5.
1.2.20
eye nce Ph um
1.2.21
enc Right m C nce d II
28
29
15:1
Week 5
1.2.21a Same embryo as in gure 1.2.21.
Week 6
1.2.181.2.29 Developmental stages of the face. Ventral-left view.
1.2.22
Embryos at week 6.
1.2.23
Med Right nce ence
1.2.24
Week 7
nce Med ce Right ear
1.2.25
Embryo at week 7.
30
31
15:1
Week 7
1.2.26 Embryos at week 7.
1.2.28
M l ear
Week 8
1.2.29
Embryo at week 8.
32
33
30:1
Week 4 / 5
e
1.2.30
1. External Aspects
H p
d II wall
Max
II d IV
1.2.32
Reg Ma d II inus
34
35
15:1
Week 5
1.2.32a Same embryo as in gure 1.2.32. In contrast to gure 1.2.32 the head is oriented such that the lower jaw lies in a nearly horizontal position.
Week 6
1.2.301.2.37 Developmental stages of the face. Left view.
1.2.33 / 34
Embryos at week 6.
Week 7
1.2.35 / 36
Embryos at week 7.
Week 8
1.2.37
Embryo at week 8.
36
37
1. External Aspects
1.3
38
nous tissue arise, and a cerebral nerve grows into them (g. 6.1.58, 6.1.59). Initially, just caudal to the mouth, the rst arch develops, which will give rise to the mandible. Shortly afterwards, the second one, called the hyoid arch, arises and then the third and the fourth one develop (g. 1.3.011.3.08). In week 6, the second arch grows in a caudal direction over the third and the fourth arches which become submerged (g. 1.3.181.3.22) forming a sort of cave, the cervical sinus. Due to ectodermal growth this cave is lled up and as a consequence the caudal rim of the second arch disappears (g. 1.3.311.3.35, 1.3.461.3.48). In week 7, the rst groove and the bordering bulges of the rst and the second arches are present, forming the external auditory duct and the foldings of the external ear (g. 1.3.361.3.61). Figures 1.3.40/1.3.41, 1.3.42/1.3.45, 1.3.46/1.3.47, 1.3.48/1.3.51, 1.3.52/1.3.53, 1.3.54/1.3.55, 1.3.56/1.3.57, 1.3.58/1.3.59, and 1.3.60/1.3.61 show the individual features of the external ear of embryos at the same developmental stage.
39
30:1
Week 4
1.3.01 Head and pharyngeal arches. Left view. Embryos at week 4.
Ph
1.3.02
1.3.011.3.22 Developmental stages of the external form of the pharyngeal arches. Lateral views. 1.3.03
1.3.04
M d III Ou Le l
40
41
30:1
Week 5
1.3.05 Head and pharyngeal arches. Right view. Embryos up to the middle of week 5.
1.3.011.3.22 Developmental stages of the external form of the pharyngeal arches. Lateral views.
Pha deve g ce
1.3.06
oop
1.3.07
42
43
30:1
Week 5
1.3.08 Head and pharyngeal arches. Right view. Embryos up to the middle of week 5.
Pha
e cus
1.3.09 / 10 1.3.011.3.22 Developmental stages of the external form of the pharyngeal arches. Lateral views.
1.3.11
Head and pharyngeal arches. Right view. Embryos in the middle of week 5.
44
45
30:1
Week 5
1.3.12 Head and pharyngeal arches. Right view. Embryos in the middle of week 5.
1. External Aspects
Pha
ye nce
1.3.011.3.22 Developmental stages of the external form of the pharyngeal arches. Lateral views.
1.3.13
Week 6
1.3.14
46
47
15:1
Week 6
1.3.14a Same embryo as in gure 1.3.14.
1.3.15 1.3.011.3.22 Developmental stages of the external form of the pharyngeal arches. Lateral views.
1.3.16 / 17
1.3.18
on Regi
48
49
15:1
Week 6
1.3.19 Head and pharyngeal arches. Right view. Embryos in the middle of week 6.
1.3.20 1.3.011.3.22 Developmental stages of the external form of the pharyngeal arches. Lateral views.
1.3.21
halon
Ph P Max
1.3.22
50
51
30:1
Week 4
1.3.23 Head and pharyngeal arches in ventral view. Embryos at week 4.
1.3.24
1.3.25
1.3.26
Head and pharyngeal arches in ventral-left view. Embryos late in week 4 and early in week 5.
Ma nd III
Week 5
1.3.27
d IV Phar
52
53
30:1
Week 5
1.3.28 Pharyngeal arches in ventral view. Embryos at week 5.
1.3.29
1.3.30
1.3.31
54
55
15:1
Week 5
1.3.31a Head and pharyngeal arches in ventral view. Embryo at week 5.
Week 6
1.3.231.3.35 Pharyngeal arches in ventral view.
1.3.32
Face and pharyngeal arches in ventral view. Embryo at the beginning or in the middle of week 6.
Week 7
1.3.33 / 34
Face and pharyngeal arches in ventral view. Embryos early and late in week 7.
Week 8
1.3.35
56
57
60:1
Week 4
1.3.36 Pharyngeal arches, left view. Embryos at week 4.
1.3.37
Week 5
1.3.38
Phar
ping
1.3.39
II Cut d IV, V
58
59
30:1
Week 5
1.3.39a Same embryo as in gure 1.3.39.
1. External Aspects 1.3 The Development of the Pharyngeal Arches 1.3.40 / 41 Pharyngeal arches, left view. Embryos at week 5.
Week 6
1.3.42 / 43
Pharyngeal arches, left view. Embryos at week 6. 1.3.4244 Ectodermal warts on arch II are not rare. Their origin and fate are unknown.
1.3.44 / 45
60
61
30:1
Week 6
1.3.46 / 47 Pharyngeal arches, left view. Embryos at week 6.
Week 7
1.3.48 / 49
1.3.50 / 51
1.3.52 / 53
62
63
30:1
Week 8
1.3.54 / 55 External ear, left view. Embryos at the beginning of week 8.
1.3.58 / 59
Week 9
1.3.60 / 61
64
65
1. External Aspects
66
1.4
67
30:1
Week 4
Regi
1.4.01
bud
Right upper limb bud. Lateral-dorsal view. Embryos early, in the middle of and late in week 4.
1.4.02
1.4.011.4.40 Developmental stages of the upper limb. 1.4.03 1.4.041.4.11 Left upper limb. Lateral view.
Week 5
Cra on
1.4.04
Embryos at week 5.
1.4.05 / 06
68
69
30:1
Week 6
arm Reg
1.4.07
Embryos at week 6.
1.4.08
arm
Reg
Week 7
1.4.09
Embryo at week 7.
70
71
30:1
Week 7
1.4.10 Embryos at week 7.
1.4.011.4.40 Developmental stages of the upper limb. 1.4.11 1.4.041.4.11 Left upper limb. Lateral view.
m
Tips
nger
72
73
15:1
Week 7
1.4.11a Same embryo as in gure 1.4.11
Week 8
1.4.011.4.40 Developmental stages of the upper limb.
m
1.4.12
Me
1.4.13
Week 9
1.4.14
74
75
15:1
Week 8
1.4.15 Embryo in the middle of week 8.
1. External Aspects 1.4 The Development of the Upper Limb 1.4.16 Embryo late in week 8.
1.4.151.4.19 Developmental stages of the left hand and the ngers. Volar view.
Week 8 / 9
1.4.17
Week 9
1.4.18
Embryo at week 9.
1.4.19
76
77
30:1
Week 4 / 5
C V
1.4.20
he C
1.4.21
1.4.011.4.40 Developmental stages of the upper limb. 1.4.22 1.4.201.4.28 Developmental stages of the upper limb. Ventral view.
1.4.23
Cut dge
1.4.24
Left
ge wall
78
79
30:1
Week 6
1.4.25 Left arm. Embryos at week 6. In the stage shown in 1.4.27, the palm has started its downward movement (pronation).
1.4.27
Week 8
1.4.28
80
81
30:1
Week 5
al Reg
1.4.29
Embryos at week 5.
al
1.4.30
1.4.31
Week 6 / 7
1.4.32 / 33
82
83
30:1
Week 5
n Di
1.4.34
Embryos at week 5.
on
1.4.35
1.4.36
Week 6
1.4.37
Embryos at week 6.
1.4.38
orta Sup
Out
84
85
30:1
Week 7
1.4.39 Embryo at week 7.
15:1
1.4.341.4.40 Developmental stages of the upper limb. Cranial view. 1.4.39a Embryo at week 7.
1.4.40
m
Embryo at the end of week 7. The thorax and the pericardial cavity have been opened.
86
87
1. External Aspects
88
1.5
89
30:1
Week 4 / 5
Rem
1.5.01
b bud Sac
1.5.02
Week 5
1.5.03 / 04
1.5.05
on Ap Sacr
90
91
30:1
Week 6
1.5.06 Embryos in the middle of week 6.
1.5.07
Apic
Week 7
1.5.08
92
93
15:1
Week 7
1.5.08a Same embryo as at week 5.
94
95
15:1
Week 8
1.5.10 Embryo at week 8.
1. External Aspects 1.5 The Development of the Lower Limb 1.5.11 Embryo at the end of week 8.
Week 9
1.5.12
Embryo at week 9.
Week 10
1.5.13
96
97
30:1
Week 5
1.5.14 Embryo at the beginning of week 5.
Reg
bud
1.5.15
1.5.141.5.22 Stages of the development of the lower limb: dorsal (1.5.141.5.19, 1.5.21), cranial (1.5.20), and caudal (1.5.22) views.
1.5.16
Week 5 / 6
ord
1.5.17
98
99
15:1
Week 5 / 6
1.5.17a Same embryo as at the end of week 5/ early in week 6.
Week 6
1.5.18
Embryo at week 6.
1.5.141.5.22 Stages of the development of the lower limb: dorsal (1.5.141.5.19, 1.5.21), cranial (1.5.20), and caudal (1.5.22) views.
Week 7
1.5.19
Embryo at week 7.
eg
1.5.20
Urina
eg
100
101
15:1
Week 7
1.5.21 Embryo at week 7. Dorsal aspect.
Week 9
1.5.22
1.5.141.5.22 Stages of the development of the lower limb: dorsal (1.5.141.5.19, 1.5.21), cranial (1.5.20), and caudal (1.5.22) views.
um Reg Co yg g
102
103
30:1
Week 5 / 6
ity
1.5.23
sac Notoc
1.5.24
1.5.25
1.5.26
104
105
15:1
Week 6
1.5.26a Embryos at week 6.
1.5.27
wall
Geni
Week 7
1.5.28 / 29
Embryos at week 7.
Week 8
1.5.30
Embryo at week 8.
ver Cut
106
107
1. External Aspects
108
1.6
109
15:1
Week 5 / 6
infe f Ri ping L
1.6.01
1.6.02
1.6.04
al tag
Sacr
Week 6
1.6.05
110
111
15:1
Week 6
1.6.06 Embryo at the end of week 6. Ventral-left aspect.
Week 7
1.6.011.6.26 Developmental stages of the external genitalia.
B Rig Ri wall
1.6.07
1.6.08
112
113
30:1
Week 5
y ein vein
1.6.09
dev
1.6.10
Week 6
1.6.091.6.21 External genitalia.
Cut e ve
1.6.11
1.6.12
Week 6 / 7
1.6.13
1.6.14
114
115
30:1
Week 7
1.6.15 Embryos in the middle and at the end of week 7.
ygeal region
Week 8
1.6.17
1.6.18
116
117
30:1
Week 8 / 9
1.6.19 Embryos at the beginning and in the middle of week 8 and early in week 9.
1.6.20
1.6.21
tag
118
119
30:1
Week 9
1.6.22 Stages of the development of the perineum. Embryos at week 9.
60:1
1.6.23 / 24
1.6.25 / 26
120
121
123
2.1
The Origin of the Deciduous Teeth In week 7, epithelial thickenings inside the upper and the lower lips grow into the underlying mesenchyme to form an external arch,
124
the vestibular lamina and an internal arch, the dental lamina (g. 2.1.27). The vestibular lamina will develop into the vestibular sulcus behind the lips, while the dental lamina gives rise to the teeth. In each dental lamina ten buds are formed; the tooth germs successively arise in aboral directions (g. 2.1.28, 2.1.29). Later on, the end of the tooth germ folds inward in an oral direction, thus forming the two-layered bell-shaped enamel organ (g. 2.1.30). The development of the materials of the teeth, the dentine, the enamel and the periodontium and also the origin of the permanent teeth is during the fetal and the postnatal period and they are therefore beyond the scope of this atlas.
The Origin of the Thyroid Gland The thyroid gland is formed by a depression in the midline of the valley between the rst and the second pharyngeal arches, the foramen caecum (g. 2.1.01). This bud develops into an endodermal pouch growing downward into the mesenchyme of the oor of the mouth (g. 2.1.33, 2.1.34). During the descent of the heart, the thyroid gland descends to the neck and its connection to the tongue is reduced to the thyroglossal duct (g. 2.1.35) which partially may remain as the pyramidal lobe. During its descent, the thyroid gland is crooked and forms two lobes connected by the isthmus.
2.1 Abbreviations IIIV pharyngeal arch IIIV 1 medial lingual swelling 2 lateral lingual swelling 3 tongue 4 epiglottis 5 laryngotracheal groove
125
40:1
Week 5
Ph
2.1.01
Embryos at week 5.
2. Endodermal Organs in the Head and Neck 2.1 The Development of the Walls of the Oral Cavity
2.1.02
Hypo ove
2.1.012.1.10 The oor of the mouth and the tongue. The brain and the upper jaw have been removed. Cranial view.
Week 6
2.1.03
Embryos at week 6.
2 II III IV
2.1.04 2
II 4 IV 5
III
126
127
40:1
Week 6
2.1.05 Embryos at the end of week 6.
2. Endodermal Organs in the Head and Neck 2.1 The Development of the Walls of the Oral Cavity
1 2
II
2.1.06
2.1.012.1.10 The oor of the mouth and the tongue. The brain and the upper jaw have been removed. Cranial view.
Regio
h II)
Week 7
2.1.07
Embryo at week 7.
128
129
40:1
Week 8
2.1.08 Embryo at week 8.
2. Endodermal Organs in the Head and Neck 2.1 The Development of the Walls of the Oral Cavity
2.1.012.1.10 The oor of the mouth and the tongue. The brain and the upper jaw have been removed. Cranial view.
Week 9
2.1.09 / 10
Embryos at week 9.
130
131
40:1
Week 5
R Pha Pha Pha Ph ng ing oove
2.1.11
Embryo at week 5.
2. Endodermal Organs in the Head and Neck 2.1 The Development of the Walls of the Oral Cavity
Week 6
2.1.012.1.37 Developmental stages of the walls of the oral cavity.
2.1.12
Embryos at week 6.
2.1.112.1.18 The oor of the mouth and the tongue. The upper head and the upper jaw have been removed. Ventral and ventral-cranial view, respectively.
2.1.13
ence g g Ou Left atrium
Week 7
2.1.14 / 15
Embryos at week 7.
132
133
40:1
Week 8
2.1.16 Embryos at week 8.
2. Endodermal Organs in the Head and Neck 2.1 The Development of the Walls of the Oral Cavity
2.1.17
2.1.112.1.18 The oor of the mouth and the tongue. The upper head and the upper jaw have been removed. Ventral and ventral-cranial view, respectively.
Week 9
2.1.18
Embryo at week 9.
134
135
40:1
Week 6
ence Med ula aw Ou g
2.1.19
Embryos at week 6.
2. Endodermal Organs in the Head and Neck 2.1 The Development of the Walls of the Oral Cavity
2.1.192.1.23 The oor of the oral cavity and the tongue. The upper head and the upper jaw have been removed. Ventral-left view.
Week 7 / 8
2.1.22 / 23
136
137
40:1
Week 6
2.1.24 Embryo at week 6.
2. Endodermal Organs in the Head and Neck 2.1 The Development of the Walls of the Oral Cavity
Med
ng
ove
Week 7
2.1.25
Embryo at week 7.
Week 8
2.1.26
Embryo at week 8.
138
139
40:1
Week 8
Low
2.1.27
2. Endodermal Organs in the Head and Neck 2.1 The Development of the Walls of the Oral Cavity
erms
Right dental lamina with early tooth germs (incisor and premolar) of the lower jaw, seen from the ventral-caudal side. The vestibular lamina has been removed. Embryo at week 8.
80:1
2.1.012.1.37 Developmental stages of the walls of the oral cavity. 2.1.28 Tooth germ of a premolar in the upper jaw. Ventral view. Embryo at week 8.
2.1.272.1.30 Early stages in the development of the teeth. 2.1.29 Incisor tooth germs of the upper jaw. Ventral view. Embryo at week 8.
Week 9
2.1.30
Early premolar bellshaped enamel organ of the right upper jaw. Caudal-ventral view. Embryo at week 9.
140
141
40:1
Week 5 / 7
2.1.31 Position of the foramen caecum. Cranial view. Embryos at weeks 5 and 7.
2. Endodermal Organs in the Head and Neck 2.1 The Development of the Walls of the Oral Cavity 2.1.32
80:1
Week 5
m bud Ou
2.1.33
160:1
2.1.34
80:1
Week 7
2.1.35 Foramen caecum and thyreoglossic duct exposed ventrally. Ventral view.
142
143
40:1
Week 8
2.1.36 Bud of the right parotic gland. The connective tissue underlying the oor of the mouth and the gland has been removed. Caudal view. Embryo at week 8.
2. Endodermal Organs in the Head and Neck 2.1 The Development of the Walls of the Oral Cavity
Pa
de ue
2.1.37
rior
144
145
2.2
146
1 2 3 4 5 6 7
2.2 Abbreviations palatal process primary palate upper jaw nasal septum auditory tube hard palate pharynx
147
40:1
Week 5
Le
2.2.01
2. Endodermal Organs in the Head and Neck 2.2 The Development of the Nose
Max hI Ph
2.2.02
2.2.03
Week 6
2.2.04
Later
ence
The right nasal pit deepens into the nasal groove. Embryos at week 6.
2.2.05
2.2.06
148
149
40:1
Week 7
Late
2.2.07
The nasal swellings arise around the nasal groove. Embryos at week 7.
2. Endodermal Organs in the Head and Neck 2.2 The Development of the Nose
jaw
2.2.08
Week 8
2.2.09
The apparently unpaired external nose has become prominent. Embryo at week 8.
150
151
40:1
Week 5
erm
2.2.10
2. Endodermal Organs in the Head and Neck 2.2 The Development of the Nose
Epit
Week 6
ium Epit ce
2.2.11
The nasal groove deepens into the nasal duct. Embryos at week 6. 2.2.11 / 12 Lateral views. 2.2.13 Ventral view.
2.2.12 2.2.102.2.23 Development of the internal aspects of the right nasal cavity. The nasal grooves/nasal ducts have been exposed and partially fenestrated to demonstrate the lumen. 2.2.13
Week 7
2.2.14
The epithelial lateral wall of the right nasal duct has been exposed. Lateral view. Embryos at week 7.
2.2.15
152
153
40:1
Week 7
m l
2.2.16
The nasal groove still does not show any communication with the oral cavity.
oove
duct
The epithelial contact between nasal and oral epithelia is torn, thus forming the primary choana.
2.2.102.2.23 Development of the internal aspects of the right nasal cavity. The nasal grooves/nasal ducts have been exposed and partially fenestrated to demonstrate the lumen. 2.2.162.2.19 The lateral epithelial wall of the right nasal duct has been removed. Embryos at week 7.
avity m
2.2.18
2.2.19
154
155
40:1
Week 8
2.2.20 Upon removal of the left nasal cavity and the medial wall of the right nasal cavity, the lateral wall, exhibiting the rst conchal bud, is shown. Left view. Embryo at week 8.
2. Endodermal Organs in the Head and Neck 2.2 The Development of the Nose
2.2.21
2.2.102.2.23 Development of the internal aspects of the right nasal cavity. The nasal grooves/nasal ducts have been exposed and partially fenestrated to demonstrate the lumen.
Upon removal of the lateral wall of the right nasal cavity, the medial wall can be seen, exhibiting the nasal septum and the organ of Jacobson. Right view. Embryo late in week 8
156
157
20:1
Week 8
2.2.22 Upon removal of the left nasal cavity and the medial wall of the right nasal cavity, the lateral wall with the conchae can be seen. Left view. More advanced stage than the embryo in gure 2.2.20.
2. Endodermal Organs in the Head and Neck 2.2 The Development of the Nose
2.2.012.2.31 Developmental stages of the nose. 2.2.23 The epithelial lateral wall of the right nasal cavity shows the foldings of the developing conchae. Right view.
2.2.102.2.23 Development of the internal aspects of the right nasal cavity. The nasal grooves/nasal ducts have been exposed and partially fenestrated to demonstrate the lumen. 2.2.22 / 23 Developmental stages of the conchae. Embryos at week 8.
Brain
nchae
158
159
20:1
Week 7
2.2.24 Embryo at week 7.
2. Endodermal Organs in the Head and Neck 2.2 The Development of the Nose
nce
Regio ch
Week 8
2.2.25
Embryo at week 8.
2.2.242.2.26 Developmental stages of the elongation of the primary choana. The lower jaw has been removed. Caudal view.
2.2.26
The right palatine process has been partly resected to show the elongation of the primary choana. Embryo late in week 8.
Cut e ess
160
161
20:1
Week 7
2.2.27 The right nasal cavity has been removed to show the epithelial medial wall of the left nasal cavity with the medial nasal nerves. Right view. Embryo at week 7.
avity
2. Endodermal Organs in the Head and Neck 2.2 The Development of the Nose
vity,
Week 8
rium m
2.2.28
gue
Both nasal cavities have been opened cranially. The connective tissue between the nasal cavities has been removed except the cartilage of the nasal septum. Cranial-dorsal view. Embryo at week 8.
2.2.29
Caudal and lateral-right view of the palatine processes and the lower free border of the nasal septum. Elevation of the palatine process has started ventrally, thus establishing the contact between it and the nasal septum. Embryo at week 8.
2.2.30 5
1 3 2 1 4
Caudal and lateral-right view of the palatine processes and the lower free border of the nasal septum. Elevation of the palatine process is advanced in the dorsal direction, thus completing the contact between it and the nasal septum. Embryo at week 8.
162
163
20:1
Week 10
3 2. Endodermal Organs in the Head and Neck 2.2 The Development of the Nose 6 2.2.31 Dorsal and caudal view of the palate and the nasal septum. The fusion of the palatine processes with each other and the free border of the nasal septum has been completed. The soft palate has been removed. Embryo at week 10.
164
165
2.3
166
1 2 3 4 5 6 7 8 9
2.3 Abbreviations palatal process, still vertical palatal process, nearly horizontal palatal processes, fusing hard palate soft palate primary palate nasal septum tongue upper jaw
167
40:1
Week 4
2.3.01 Oral cavity. Ventral view. Embryo at week 4.
wall
Week 5 / 7
2.3.02
Oral cavity. Caudal view. The lower jaw has been removed. Embryos at weeks 5 and 7.
2.3.03
ence ence
pouch, orice
168
169
20:1
Week 7
2.3.03a Same embryo as in gure 2.3.03.
2. Endodermal Organs in the Head and Neck 2.3 The Development of the Palate
2.3.04 9 6 1 1
The lower jaw and the oor of the oral cavity except the tongue have been removed. Caudal view. Embryo late in week 7.
2.3.05 9 6
Same embryo as in gure 2.3.04. After removal of the tongue, the future nasal cavity is visible. Caudal view.
Week 8
9 6 8 1 1
2.3.06
The lower jaw and the oor of the oral cavity except the tongue have been removed. Caudal view. Embryo at week 8.
170
171
20:1
Week 8
9 2.3.07 Same embryo and the same state of dissection as in gure 2.3.06. The ventral view shows the position of the tongue and the palatal processes. Ventral view.
2. Endodermal Organs in the Head and Neck 2.3 The Development of the Palate
Same embryo as in gure 2.3.07. After removal of the tongue, the palatal processes and the future nasal cavity are visible. Caudal view.
2.3.09 9 6
The lower jaw and the tongue have been removed. More advanced elevation of the palatal processes. Embryo late in week 8. Caudal view.
2 7
172
173
20:1
Week 8
9 2. Endodermal Organs in the Head and Neck 2.3 The Development of the Palate 1 2.3.10 In this embryo the elevation of the palatal processes is not right-left symmetrical. Embryo late in week 8 (see g. 2.4.04). Due to the more advanced elevation of the left palatal process, the tongue is presented in an oblique position. Caudal view.
8 2
2.3.11
Same embryo as in gure 2.3.10. The tongue has been removed to show the asymmetrical positions of the palatal processes. Ventral view.
Week 9
6 9
2.3.12
The lower jaw and the tongue have been removed. The elevation of the palatal processes is advanced and their fusion has begun ventrally. Embryo at week 9. Caudal view.
174
175
20:1
Week 10
9 2. Endodermal Organs in the Head and Neck 2.3 The Development of the Palate 4 4 2.3.13 Embryo at week 10. Caudal view. The lower jaw and the oor of the oral cavity, except the tongue, have been removed. The palate is partly hidden behind the tongue.
2.3.14 9
Embryo at week 10. Caudal view. After removal of the tongue, the hard and the soft palate are visible.
176
177
2.4
The Hypopharynx The relief of the hypopharynx is formed by the internal surfaces of the pharyngeal arches III and IV (g. 2.4.07, 2.4.08). The median parts of these arches swell out and form the hypopharyngeal eminence (g. 2.4.09, 2.4.10). The caudal border of the hypopharynx is formed by the sixth arches (g. 2.4.072.4.09) which eventually take part in the formation of the arytenoid swellings of the larynx (g. 2.4.09, 2.4.10). The position of the pharyngeal arch arteries in relation to the pharyngeal arches is shown in gures 2.4.122.4.14.
178
II III IV 1 2 3 4 5 6 7 8
2.4 Abbreviations pharyngeal arch II pharyngeal arch III pharyngeal arch IV medial lingual swelling lateral lingual swelling tongue epiglottis laryngotracheal groove palatal process auditory tube pharynx
179
20:1
Week 5
2.4.01 Oral cavity and pharynx. The lower jaw and the oor of the oral cavity have been removed. Embryos at weeks 5, 7 and 8. Ventral views.
2. Endodermal Organs in the Head and Neck 2.4 The Development of the Pharynx
Week 7
2.4.02
Week 8
2.4.03
7 8
180
181
20:1
Week 8
2.4.04 The position of the orice of the auditory tube. Same embryo as in gures 2.3.10 and 2.3.11. The lower jaw and the oor of the oral cavity have been removed. Caudal view.
2. Endodermal Organs in the Head and Neck 2.4 The Development of the Pharynx
Palat seen
sition
Week 10
2.4.05
Pa Pal
esses
Ventral view of the hard and the soft palate and the palatine tonsil, the palatopharyngeal and the palatoglossal arches. The lower jaw and the oor of the oral cavity have been removed. Embryo at week 10.
80:1
2.4.06 Anlage of the palatine tonsil. Embryo at week 10. Ventral view.
182
183
40:1
Week 5
2.4.07 Cranial-dorsal view of the pharyngeal region of the tongue and the pharynx. Embryos at weeks 5 (2.4.07, 2.4.08), 6 (2.4.09, 2.4.10) and 7 (2.4.11).
2. Endodermal Organs in the Head and Neck 2.4 The Development of the Pharynx
For
d II nd IV e
Week 5 / 6
2 1 2.4.012.4.14 Developmental stages of the pharynx. II III IV 4 IV 5III II 2 1 2
2.4.08 / 09
Week 6 / 7
3 1 2 2
2.4.10 / 11
II 4 5III II III
184
185
40:1
Week 5
La pha tery IV ery VI
2.4.12
2. Endodermal Organs in the Head and Neck 2.4 The Development of the Pharynx
L pha
Positional relationships of the pharyngeal arch arteries. Dorsal view. Embryos at weeks 5 (2.4.12, 2.4.13) and 6 (2.4.14).
2.4.13
Oric ry III ry IV ry VI
Week 6
Or ry III ry IV ry VI
2.4.14
186
187
188
2.5
I II III IV 1 2 3 4 5 6 8 9 10
2.5 Abbreviations pharyngeal arch I pharyngeal arch II pharyngeal arch III pharyngeal arch IV medial lingual swelling lateral lingual swelling foramen caecum epiglottis laryngotracheal groove arytenoid swelling pharynx oesophagus trachea
189
100:1
Week 4
2.5.01 External and internal aspects of the early laryngeal region and the lung buds. Embryos at weeks 4 (2.5.01, 2.5.02) and 5 (2.5.03, 2.5.04). Ventral-left view.
2. Endodermal Organs in the Head and Neck 2.5 The Development of the Larynx
ynx Oe
Week 5
2.5.03
2.5.04
190
191
50:1
Week 5
3 2. Endodermal Organs in the Head and Neck 2.5 The Development of the Larynx 5 I II III IV 2.5.05 Dorsal view of the hypopharynx and the branching o of the larynx. Embryos at weeks 5 (2.5.052.5.07) and 6 (2.5.08).
2.5.06
2.5.07
Ph Ph Ph L ence ve
Week 6
1 2 3 II 4 IV III 2
2.5.08
192
193
50:1
Week 6
2.5.09 / 10 Cranial view of the laryngotracheal groove. Embryos late in week 6. Individual variations in embryos at the same developmental stage.
2. Endodermal Organs in the Head and Neck 2.5 The Development of the Larynx
Week 7
2.5.012.5.13 Developmental stages of the larynx.
2.5.11
Week 6
Parathyroid gland and thymus Right pharyngeal arch artery III Pericardial cavity Pharynx, lumen Epithelial lamina of the larynx Left pharyngeal arch artery III Ascending aorta
2.5.12
Week 8
8 6
2.5.13
Ventral-right view of the pharynx, the larynx and the oesophagus. Embryo at week 8.
10 9
194
195
196
2.6
197
50:1
Week 5 / 6
I
2.6.01
2. Endodermal Organs in the Head and Neck 2.6 The Position of the Thymus and the Parathyroid Glands
Th
II h III d
2.6.02
2.6.01 / 02 Lateral left view of the exposed epithelial buds of the anlage of the thymus and the superior parathyroid. Same embryo at the end of week 5/ beginning of week 6.
The connection of the thymus to the pharyngeal pouch is cut. The superior parathyroid has been removed.
2.6.03
gland Pha
Ventral-left view of the position of the thymus and the parathyroid. The most ventral portion of the thymus has been removed. Embryo at the end of week 6.
198
199
100:1
Week 6
2.6.04 Ventral-right view of the right thymus. The supercial surrounding tissue has been removed to show the ectodermal part. Embryo at the end of week 6.
2. Endodermal Organs in the Head and Neck 2.6 The Position of the Thymus and the Parathyroid Glands
200:1
2.6.012.6.06 Position of the thymus. 2.6.05 Same region at a higher magnication to show the structure of the thymus anlage.
50:1
Week 8
2.6.06 Ventral-right view of the thymus. Embryo at week 8.
V Va
ture
200
201
203
3.1
Interior of the Heart: The Cardiac Septation In week 4, the young cardiac loop resembles a tube which is curved in an intricate way. It pumps the blood from the inow to the outow tract in an undivided ow path. In the heart of the adult, however, there are two separate ow paths, the pulmonary and the systemic (aortic), which are completely separated under
204
normal conditions. Additionally, each of these ow paths is organized into two chambers, an inow chamber, the atrium, and an outow chamber, the ventricle. The transformation of the undivided ow path into two denite paths is realized by a system of septa which arise at the dierent levels of the loop. These septa join up to build a partition wall which divides the undivided bloodstream into the pulmonary and the systemic stream. There are two kinds of septa, primarily paired mesenchymal and unpaired muscular septa. The process of septation occurs in the following manner: the paired septa arise as superior and inferior atrioventricular septa (cushions) between the inow tract (atria) and ventricles (g. 3.1.303.1.32); and also between the ventricular region and the outow tract as right and left conus septum (g. 3.1.33, 3.1.34); thirdly, they arise as superior and inferior truncus septa on the boundary between upstream and downstream regions of the outow tract (g. 3.1.35). The opposing septa in each region grow into the lumen almost at right angles to the bloodstream, their free edges come into contact and eventually they fuse to form a uniform unpaired septum (e.g. g. 3.1.36, 3.1.37). Meanwhile, the primarily unpaired muscular septa are formed. Starting from the external cardiac wall they fold up into the lumen of the inow tract as interatrial septum (g. 3.1.453.1.47) and into the lumen of the ventricular region as the interventricular septum (g. 3.1.36, 3.1.37). The more complicated septation in the atria will be described later. In a second phase of septation the septa of the neighbouring levels connect to each other in a direction parallel to the bloodstream: the atrial septum connects with the atrioventricular septa (cushions) (g. 3.1.50, 3.1.51). The inferior atrioventricular cushion connects to the posterior margin of the interventricular septum (g. 3.1.38) and the anterior margin of the interventricuar septum connects to the left portion of the conus septum (g. 3.1.37, 3.1.38). The right conus septum connects via the superior and the inferior atrioventricular cushions to the posterior margin of the interventricular septum (g. 3.1.36, 3.1.39, 3.9.40). Before the denite fusion of these septa in the ventricular region is realized, a fora-
205
men between the right and the left ventricular ow paths remains open (g. 3.1.393.9.41). This interventricular foramen is closed by the middle or the end of the 3rd month. In the outow tract, the conus septa connect to the truncus septa in the following way: the left conus septum connects to the inferior truncus septum (g. 3.1.37) and the right conus septum connects to the superior truncus septum (g. 3.1.36, 3.1.38). Septation is completed by the aorticopulmonary septum which arises in the aortic sac between the systemic and pulmonary pharyngeal arch arteries (g. 3.1.42, 3.1.43). It grows in an upstream direction and connects with its limbs to the superior and the inferior truncus septa (g. 3.1.44). Atrial septation is a little more intricate because there is a second muscular septum (septum secundum) independent of the already mentioned septum (primum). As noted above, the septum primum arises rst by ingrowth from dorsal into the atria (g. 3.1.453.1.47). At the base of the heart, its limbs connect to the atrioventricular cushions (g. 3.1.50, 3.1.51). During the ingrowth of the septum primum, below its free rim a communication between the atria remains open: the foramen primum (g. 3.1.47). Simultaneously the septum primum is perforated in its upper parts, thus establishing a second communication between the atria, the foramen secundum (g. 3.1.483.1.50, 3.1.52). The foramen primum becomes reduced in size until it is eventually closed during the 3rd month. The foramen secundum increases in size until it reaches about half of the area of the septum primum. No earlier than in the 3rd month does the second interatrial septum arise, the septum secundum. It arises to the right of the septum primum and grows from ventral to dorsal (g. 3.1.53). The septum secundum remains incomplete and almost covers the free rim of the septum primum. In this way the nal embryonic and fetal communication between the atria, the foramen ovale is established. It is bordered by the superior rim of the septum primum and the inferior rim of the septum secundum. The foramen ovale is closed shortly after birth by the increasing pressure in the left atrium. There are extreme individual variations in the moment of realization of the second phase of septation, in which the septa of
206
the neighbouring regions connect to each other. Additionally, the origin of the septa in the rst phase of septation is not realized in the order described. It was not the goal of the description to give a time schedule of the septation, but to give an outline of the septal topography. Missing or incomplete or dystopic development of the septa and an abnormal connection of septa may well be the formal cause of a great variety of cardiac malformations.
la lv ra rv 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21
3.1 Abbreviations left atrium left ventricle right atrium right ventricle sinus venosus ventricular loop interventricular sulcus outow tract, conus outow tract, truncus pulmonary trunk ascending aorta aortic arch atrioventricular sulcus anterior descending branch of left anterior coronary artery anterior leaet of the tricuspid valve septal leaet of the tricuspid valve anterior papillary muscle posterior papillary muscle supraventricular crest pulmonary semilunar valve common cardinal vein hepatic vein superior cardinal vein right sinus valve left sinus valve
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40:1
Week 4
3.1.01 / 02 / 03 Same embryo at week 4. Right, ventral, and left views.
1 2 2
3.1.04
3.1.013.1.29 Development of the external form of the heart. Right, ventral, and left views.
4 2
3.1.05
4 2
3.1.06 / 07 / 08 4 4 2 2 Iv Ia 5
Same embryo at the end of week 4. Right, ventral, and left views.
Week 5
4
3.1.09
Iv rv 3
208
209
40:1
Week 5
5 4 3. Organs in the Thorax 3.1 The Development of the Heart 4 ra Iv Iv rv rv Ia 3.1.10 / 11 / 12 Same embryo at week 5. Right, ventral, and left views.
3.1.13
3.1.013.1.29 Development of the external form of the heart. Right, ventral, and left views.
3.1.14 5
3.1.15 / 16 / 17 5 4 Iv ra rv 17 18 3.1.18 ra rv 3 Iv Iv rv 4 4 5 Ia
Same embryo at the end of week 5. Right, ventral, and left views.
Week 6
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211
40:1
Week 6
7 3. Organs in the Thorax 3.1 The Development of the Heart 6 7 6 3.1.19 / 20 3.1.19 Embryo early in week 6. 3.1.20 Embryo at the end of week 6. Ventral view.
3.1.013.1.29 Development of the external form of the heart. Right, ventral, and left views.
Week 7
3.1.21
212
213
40:1
Week 7 / 8 / 9
8 3. Organs in the Thorax 3.1 The Development of the Heart 7 7 6 6 8 3.1.22 / 23 Embryos at weeks 7, 8 and 9. Ventral views.
3.1.013.1.29 Development of the external form of the heart. Right, ventral, and left views.
3.1.24
214
215
40:1
Weeks 5 / 6 / 8
7 3. Organs in the Thorax 3.1 The Development of the Heart 6 3.1.25 / 26 Embryos at weeks 5, 6 and 8. Left views.
3.1.013.1.29 Development of the external form of the heart. Right, ventral, and left views.
3.1.27
216
217
40:1
Weeks 6 / 9
3.1.28 / 29 Embryos at weeks 6 and 9. Right views.
3.1.013.1.29 Development of the external form of the heart. Right, ventral, and left views.
218
219
50:1
Week 6
Supe
3.1.30
ial Infe
3.1.31
hion
passin
Tra
on
3.1.33 / 34
Position of the conus (3.1.33, 3.1.34) and the truncus (3.1.35) septa. View in a downstream direction. Embryos at week 6.
Larynx
3.1.35
Cut a
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221
50:1
Week 7
Truncus
3.1.36
Intercalated ridge of the pulmonary valve Connecting ridge between the right conus septum and superior truncus septum Tricuspid orice Anterior papillary muscle Connecting ridge between the left conus septum and inferior truncus septum Superior atrioventricular cushion Inferior atrioventricular cushion
The broken line indicates the boundary of the interventricular foramen still wide open. Whereas the left portion of the interventricular septum has already been formed, the septal protrusions forming the right portion have not yet advanced to the corresponding portion of the broken line. (Compare with the more advanced stage in g. 3.1.39.)
3.1.37
I l d id lve um
3.1.363.1.40 Stages of the connection of the conus septa with the ventricular septum and the truncus septa. Dierent devopmental stages of the closure of the interventricular foramen. Ventral-right view of the right ventricle. Embryos at week 7.
Connection of the interventricular septum via the left conus septum to the inferior truncus septum. The corresponding connection of the right conus septum to the superior truncus septum has been removed.
3.1.38
P l Con l conus
Super
222
223
50:1
Week 7
3.1.39 Dierent stages of the development of the interventricular foramen.
pulm int
3.1.40
3.1.363.1.40 Stages of the connection of the conus septa with the ventricular septum and the truncus septa. Dierent devopmental stages of the closure of the interventricular foramen. Ventral-right view of the right ventricle. Embryos at week 7.
Week 8
3.1.41
ed I Trab se ft m
Left view into the left ventricle shows the interventricular foramen and the outow tract of the left ventricle (aortic conus). Embryo at week 8.
224
225
100:1
Weeks 5 / 6 / 7
3.1.42 View in a downstream direction into the aortic sac and the origin of the third, fourth and sixth aortic arch arteries.
Caro eptum
3.1.423.1.44 Septation of the truncus (distal outow tract) and the aortic sac. Embryos at weeks 5, 6 and 7.
3.1.43
y IV
tum ct
Same view as in gure 3.1.42. The more protruded aorticopulmonary septum now separates the pulmonary from the systemic ow path, which gives rise to the third and fourth aortic arch arteries.
3.1.44
Supe P Infe
Lateral left view of the distal truncus. The connection of the aorticopulmonary septum to the truncus septa is nearly complete, and separates the pulmonary from the systemic ow paths.
226
227
50:1
Week 5
3.1.45 Origin of the primary interatrial septum. Ventralright and ventral view. Embryos early in week 5.
Le Rig C
um
3.1.46
Cut e
l vein
3.1.47 / 48
Lateral (left) view of the opened left atrium. 3.1.47 The wide open interatrial foramen primum. 3.1.48 The rst indication of the interatrial foramen secundum. The rst foramen is hidden beneath the atrial wall.
3.1.49 / 50
Lateral (left) view of the opened left atrium. The interatrial foramen secundum has become enlarged.
228
229
50:1
Week 7
3.1.51 Closure of the primary interatrial foramen. Cranial-right view of the atrioventricular cushions and the primary interatrial foramen. The walls of the right atrium have been removed. Embryo at week 7.
Week 8
3.1.52
Closure of the primary interatrial foramen. Left view of the left atrium. The secondary foramen has become enlarged (see g. 3.150), the primary foramen is now only a very small opening. Embryo at week 8.
ium Su Cut en
Week 10
3.1.53
Origin of the secondary interatrial septum and the foramen ovale. Right view of the right atrium. Embryo at week 10.
Prim
valve
230
231
50:1
Week 6
19
dium um Right h um ns g p Right lobe of the liver
3.1.54
The right atrium has been opened to show the right venous valve.
17
20
3.1.453.1.56 Septation of the atria. 19 3.1.543.1.56 Orice of the common, the superior and the inferior cardinal veins and the hepatic vein into the right atrium, and the sinus valves. Consecutive dissections of an embryo at week 6.
pened Trian
3.1.55
17
20
3.1.56
19
Oric
17
er
The right sinus valve and its origin from the atrial wall are removed to show the left sinus valve and the opening of the hepatic (future inferior caval vein) into the right atrium.
21 18
232
233
50:1
Week 5
wall
3.1.57 / 58
3.1.57 Lateral (left) view of the heart. Embryo at week 5. 3.1.58 Caudal view of the opened left ventricle. Embryo at week 5.
n ptum inte
Week 7
3.1.573.1.68 Developmental stages of the cardiac valves.
eaet Aort
3.1.59
Ventral and caudal view of the opened left ventricle. Embryo at week 7.
Week 9
3.1.60
Ao post
cut
Ventral and caudal view of the opened left ventricle. The leaets of the mitral valve have been partly removed to show the connection to the left atrium. Embryo at week 9.
234
235
50:1
Week 6
3.1.61 Ventral-right view of the right ventricle. Embryo at week 6.
atri ortion
conus
Week 9
7 6
3.1.63
15
11
13
236
237
50:1
Week 9
7 16 3. Organs in the Thorax 3.1 The Development of the Heart 3.1.64 Same embryo as in gure 3.1.63. Ventral-right view of the right ventricle. The mural leaet of the tricuspid valve has been removed to show the septal leaet.
100:1
Weeks 7 / 8
3.1.65 / 66 / 67 Ventral view of the opened and vertically adjusted pulmonary trunk. Due to the opening of the trunk, the anterior leaet has been removed. Embryo at week 7, late in week 7 and at week 8.
Week 9
3.1.68
238
239
60:1
Week 5
3.1.69 Ventral-left view of the opened left pharyngeal arch arteries and the aorta. Embryo at week 5.
y III y IV y VI
Week 6
3.1.70
Rem
vein
Ventral-left view of the left fourth aortic arch artery (ascending aorta and aortic arch), the left sixth aortic arch artery (pulmonary trunk and arterial duct), and the descending aorta. Embryo at week 6.
240
241
30:1
Week 6
3.1.70a Same embryo as in gure 3.1.70.
Week 9
3.1.71
Pulm
left f
Ventral-left view of the left fourth aortic arch artery (ascending aorta and aortic arch), the left sixth aortic arch artery (pulmonary trunk and arterial duct) and the descending aorta. Embryo at week 9.
Week 10
3.1.72
Ventral-left and caudal view of the pulmonary trunk with the orices of the left and the right pulmonary arteries, and the arterial duct (ductus arteriosus), and the ascending aorta and the aortic arch (regarding the position of the orices of the pulmonary arteries: see g. 3.1.71). Embryo at week 10.
3.1.73
y rtery Oric
ori Rem
242
243
60:1
Week 4
3.1.74 The exits of the sixth aortic arch arteries are not yet apparent. Embryo at week 4.
Ph Pha
y II y III y IV
Week 5
y III A y IV y VI
3.1.75
The exits of the sixth aortic arch arteries are situated laterally. Embryo at week 5.
3.1.76 3.1.743.1.78 Septation of the aortic sac. View in a downstream direction of the aortic sac and the exits of the pharyngeal arch arteries.
The exits of the sixth aortic arch arteries have approached the midline. Embryo at week 5.
ating IV ery VI
Week 6
y III y IV y VI Infe
3.1.77
The septum separating the third and fourth aortic arch arteries (caroticoaortic septum) has approached the midline. Embryo at week 6.
Week 5
Carot ph ery IV
3.1.78
The distal outow tract of the heart has been removed to show the proximal opened sixth aortic arch arteries. Embryo at week 5.
244
245
60:1
Week 6
3.1.79 Less and more advanced stages of early development of the aorticopulmonary septum. Embryos at week 6.
y IV, V Right
y III y IV
3.1.80
Aortic
ptum
Week 5
IV, V
3.1.81
Ventral-left view of the left fourth and sixth aortic arch arteries. Embryo late in week 5.
Left a ry VI,
3.1.82
Ventral view of the sixth aortic arch arteries. The distal outow tract of the heart has been removed. Embryo at week 5.
Righ ry VI
246
247
60:1
Week 6
Brac
3.1.83
Cranial and ventral view of the aortic outow tract (ascending aorta). The aorticopulmonary septum separates the systemic and the pulmonary ow paths completely.
3.1.84
cut
Same embryo as in gure 3.1.83. Cranial and ventral-left view shows the pulmonary trunk beneath the ascending aorta.
3.1.85
y III y IV
Ventral view of the positions of the third and fourth aortic arch arteries. The distal outow tract of the heart has been removed. Embryo at week 6.
3.1.86
II Ph ween
Ventral and left view of the positions of the third and fourth aortic arch arteries. The distal outow tract of the heart has been removed. Embryo at week 6.
248
249
60:1
Week 5
3.1.87 The aortic sac and the third and fourth aortic arch arteries. Embryo at week 5.
Pha
ove
3.1.88
120:1
3.1.89 Same embryo as in gure 3.1.88. Parts of the sixth arches have been removed to show the exits of the sixth aortic arch arteries.
ic sac Left p
250
251
60:1
Week 6
3.1.90 Aortic sac and third, fourth and sixth aortic arch arteries. Embryo at week 6.
cus
Week 5
3.1.91
The paired dorsal aortae with the orices of the pharyngeal arch arteries. Embryo at week 5.
Oric
ove Oric
252
253
3.2
254
by the pleuroperitoneal folds (g. 3.2.61, 3.2.62). A small pleuroperitoneal communication may be preserved up to the 3rd month (g. 3.2.63). The dierences in the development of the external form of the right and the left lung are shown in gures 3.2.333.2.48.
d il la lv mn ra rv s 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17
3.2 Abbreviations diaphragm intestinal loop left atrium left ventricle mesonephros right atrium right ventricle stomach lung bud superior lobe of the lung middle lobe of the lung inferior lobe of the lung common cardinal vein superior cardinal vein inferior cardinal vein superior caval vein left sinus horn triangular ligament pleuroperitoneal canal, coelomic duct conus truncus ductus venosus duodenum liver hepatic vein
255
60:1
Week 4
3.2.01 The lung bud is only a tiny epithelial outpocketing. Embryo at week 4.
Cut ud
3.2.02
lium
3.2.013.2.12 Early developmental stages of the lung. The heart has been removed. Ventral view.
Ventral (g. 3.2.02) and ventral-left (g. 3.2.03) view of the lung bud. Same embryo at week 4, more advanced stage.
3.2.03
elium
Caud
3.2.04
C d III
Per
The heart has been removed. Dorsal wall of the pericardial cavity and rst dichotomic ramications of the bud into the anlage of the right and the left lung. The overlying mesenchyme has been removed. Embryo at week 4.
256
257
60:1
Week 5
3.2.05 / 06 3.2.05 Right and left lung bud. The overlying mesenchyme and the epithelium of the serosa have been removed. Embryo at week 5. 3.2.06 Right and left lung buds. The overlying mesenchyme and the epithelium of the serosa have been removed. More advanced embryo at week 5.
3.2.013.2.12 Early developmental stages of the lung. The heart has been removed. Ventral view.
Right l
3.2.07
all
pleura
External aspect of the serosa epithelium that covers the lungs. The developmental stage corresponds to the embryo of gure 3.2.06.
Week 6
3.2.08 / 09
Fig. 3.2.08 The serosa and the mesenchyme overlying the endoderm have been removed. The lung anlagen have been opened. Embryo at week 6. Fig. 3.2.09 The lungs have been opened. The rst indications of the developing lobes. Embryo at week 6.
258
259
60:1
Week 6
3.2.10 The lungs have been opened. The middle lobe of the right lung is more advanced. Embryo at week 6.
Sup bud M In ud
3.2.013.2.12 Early developmental stages of the lung. The heart has been removed. Ventral view.
3.2.11
Righ S us d d
3.2.12
260
261
40:1
Week 5
ra 3. Organs in the Thorax 3.2 The Development of the Lungs 5 17 rv 16 11 ra 1 3.2.13 / 14 Embryos at week 5.
3.2.15 / 16 3.2.133.2.21 Positional development of the right lung. The adjacent pictures show dierent dissection steps of the same embryo. Pictures on the left show aspect of the opened peritoneal cavity. In the pictures on the right the structures overlying the lung have been removed to reveal the entire lung. Lateral (right) view.
6 ra 1 rv 16 11 16 rv mn ra
7 1
mn
Week 6
6
3.2.17 / 18
7 5 ra 10 1 d rv 17 1 ra
16 mn
16
262
263
40:1
Week 6
6 6 5 3. Organs in the Thorax 3.2 The Development of the Lungs mn 7 10 4 4 16 mn 3.2.133.2.21 Positional development of the right lung. The adjacent pictures show dierent dissection steps of the same embryo. Pictures on the left show aspect of the opened peritoneal cavity. In the pictures on the right the structures overlying the lung have been removed to reveal the entire lung. Lateral (right) view. s 9 ra 7 2 3 5 ra 3.2.19 / 20 Embryos early and late in week 6.
Week 7
3.2.21
rv 2
The lung has almost reached its adult position in the region between heart and liver. Only the costal pleura has been removed. The separation of the pleural and the peritoneal cavities is almost complete (see g. 3.2.63).
ra 3 4 14
16
15 mn
264
265
40:1
Week 5
6 3. Organs in the Thorax 3.2 The Development of the Lungs Ia 9 Iv d 16 16 s 3.2.22 / 23 Embryos at week 5.
7 1
3.2.223.2.32 Positional development of the left lung. The adjacent pictures show dierent dissection steps of the same embryo. Pictures on the left show aspect of the opened peritoneal cavity. In the pictures on the right the structures overlying the lung have been removed to reveal the entire lung. Lateral (left) view.
mn
3.2.24 / 25
mn
3.2.26 / 27
16
266
267
40:1
Week 6
13 2 4 Iv rv 5 s 16 3.2.223.2.32 Positional development of the left lung. The adjacent pictures show dierent dissection steps of the same embryo. Pictures on the left show aspect of the opened peritoneal cavity. In the pictures on the right the structures overlying the lung have been removed to reveal the entire lung. Lateral (left) view. 4 Ia 3.2.28 / 29 Embryo at week 6.
Week 7
3.2.30 / 31
Embryo at week 7.
9 9 7 4 16 4 16 s s il mn 2
268
269
40:1
Week !
3.2.32 The lung has almost reached its adult position in the region between heart and liver. Only the costal pleura has been removed. The separation of the pleural and the peritoneal cavities is almost complete (see g. 3.2.63).
2 3.2.223.2.32 Positional development of the left lung. The adjacent pictures show dierent dissection steps of the same embryo. Pictures on the left show aspect of the opened peritoneal cavity. In the pictures on the right the structures overlying the lung have been removed to reveal the entire lung. Lateral (left) view.
Iv 4
16
270
271
40:1
Week 5
ra 3. Organs in the Thorax 3.2 The Development of the Lungs 11 1 9 Ia 1 3.2.33 / 34 Embryo at week 5.
Week 6
3.2.35 / 36
Embryo at week 6.
3.2.333.2.48 Development of the external form of the lungs. The pictures on the right show the right lung in the lateral (left) view. The pictures on the right show the left lung in the lateral (left) view.
3.2.37 / 38
3.2.39 / 40
Week 7
3.2.41 / 42
Embryo at week 7.
272
273
40:1
Week 7
8 3.2.43 / 44 Embryo at week 7.
3.2.333.2.48 Development of the external form of the lungs. The pictures on the left show the right lung in the lateral (right) view. The pictures on the right show the left lung in the lateral (left) view.
Week 8
3.2.45 / 46
Embryo at week 8.
274
275
40:1
Week 9 / 10
3.2.47 / 48 3.2.47 Right lung. Lateral (right) view. Embryo at week 9. 3.2.48 Left lung. Lateral (left) view. Embryo late in week 9 or 10.
3.2.333.2.48 Development of the external form of the lungs. The pictures on the left show the right lung in the lateral (right) view. The pictures on the right show the left lung in the lateral (left) view.
276
277
40:1
Week 7
3.2.49 / 50 3.2.49 Ventral view of the rst lobular alveoles. Embryo at week 7. 3.2.50 Dorsal view of the right lung. Embryo at week 7.
Week 8
3.2.51 / 52 / 53
3.2.51 Ventral view of the lungs. Embryo at week 8. 3.2.52 Lateral (right) view of the middle lobe of the right lung. Embryo late in week 7. 3.2.53 Lateral (right) view of the middle lobe of the right lung. Embryo at week 8.
3.2.54
Lateral (right) view of the superior and the middle lobe of the right lung. Embryo at week 8.
278
279
30:1
Week 4
3.2.55 Lateral (left) view. The pericardial and coelomic cavities have been opened. Embryo at week 4.
ng the
I anal
Same embryo as in gure 3.2.55. Ventral-left view. The heart has been removed. After the removal of the left common cardinal vein, the connection between the pericardial and the peritoneal cavities is visible: the left coelomic duct (pericardioperitoneal duct).
3.2.57
Lateral (right) view. The right common cardinal vein has been removed and the right coelomic duct in its positional relationship to the lung is shown. Embryo at week 4.
Week 5
d III
3.2.58
Ventral-right view. The heart and the common cardinal vein have been removed to show the positional relationship of the right lung to the coelomic duct. Embryo at week 5.
3.2.59
Right l
280
281
30:1
Week 5
Pha Su Co Ple um
3.2.60
Lateral (right) view. The part of the right lung that is not covered by the common cardinal vein. Embryo at week 5.
3.2.61
D
sum Dors
Lateral (right) view. The common cardinal vein has been removed and the endoderm of the lung is exposed. The rst indication of the fold separating the pleural from the peritoneal cavity is visible. Embryo at week 5.
Week 6
3.2.62
Pleuro
Ventral-right view. After removal of the right common cardinal vein the pleural surface of the entire lung is visible. Embryo at week 6.
rsum
Week 8
3.2.63
Cranial view of the oor of the left pleural cavity (diaphragm). A tiny communication between pleural and peritoneal cavities is still present. Embryo at week 8.
282
283
285
4.1
286
il lv mn ra rv s 2 3 4 5 6 7
4.1 Abbreviations intestinal loop left ventricle mesonephros right atrium right ventricle stomach liver, left lobe liver, right lobe bare area of the liver lung bulge of the kidney genital tubercle
287
40:1
Week 4
ersum
4.1.01
Extra o
Closure of the endodermal gut plate forms the intestinal tube. Dierent developmental stages in embryos at week 4. Ventral view.
4.1.02
culum sicle
4.1.03
4.1.04
Right l avity
cle
288
289
40:1
Week 4
4.1.05 Closure of the endodermal gut plate forms the intestinal tube. Dierent developmental stages in embryo at week 4. Ventral view.
duct Supe
Week 5
4.1.06
Ventral view of the peritoneal cavity. The liver has been removed. Embryo at week 5.
4.1.07 3 4 rv lv mn ra
Ventral right view of the rst bend of the intestinal tube. Embryo at week 5.
290
291
20:1
Week 5
4.1.07a Same embryo as in gure 4.1.07.
4. Organs in the Abdomen 4.1 The Development of the Small Intestine 4.1.08 Ventral and ventral-right views of an embryo at the end of week 5.
4.1.09
Week 5 / 6
4.1.10
Ventral view of the intestinal loop. Embryo at the end of week 5/ beginning of week 6.
Sup
, cut
292
293
20:1
Week 5 / 6
4.1.11 Same embryo as in gure 4.1.10. Ventral-right view. The body wall has been removed.
Week 6
4.1.014.1.19 Developmental stages of the gut.
4.1.12
Ventral-right view of the intestinal loop. The liver has been removed. Embryo at week 6.
4.1.13
Ventral-right view of the intestinal loop and the stomach. The liver has been removed. Embryo at the end of week 6.
Week 7
4.1.14
Ventral-right view of the intestinal loop and the stomach. The liver has been removed. Embryo at week 7.
4.1.15
294
295
20:1
Week 7
5 4.1.16 Lateral-left view of the intestinal loop, liver, stomach, and mesonephros. Embryo at week 7.
mn s
il 6 7
4.1.17 / 18 3 4 2
il
4.1.17 Ventral-right view of the intestinal loop, duodenum, and stomach. The liver has been removed. Embryo at week 7. 4.1.18 Ventral view of the intestinal loop and the liver. Embryo at week 7.
Week 9
4.1.19
296
297
4.2
298
this ductus venosus gives rise to a multitude of small veins (g. 4.2.23) which drain into sinusoids and eventually form branches of the portal system. The ductus venosus atrophies after birth.
bw il l la lv mn ra rv s 1 2 3 4 5 6 11 12 13 14
4.2 Abbreviations cut edge of the body wall intestinal loop lung left atrium left ventricle mesonephros right atrium right ventricle stomach liver, right lobe bare area of the liver liver, left lobe umbilical vein, orice portal vein subcardinal-hepatic anastomosis duodenum genital tubercle hepatic vein/hepatic portion of inferior caval vein venous duct
299
50:1
Week 4
4.2.01 Ventral view of the midgut plate and the orice of the hepatic diverticulum. Embryo early in week 4.
Mese
atic
Ventral view of the more folded midgut plate and the orice of the hepatic diverticulum. Embryo at week 4.
Orice Cut
port
4.2.03
Same embryo as in gure 3.2.01. The hepatic diverticulum has been opened.
ened
300
301
50:1
Week 5
4.2.04 Ventral view of the endodermal hepatic bud. The adjacent mesenchyme of the transverse septum has been removed. Embryo at week 5.
lum
Week 4
4.2.05
Left and caudal view of the peritoneal cavity showing the external appearance of the left lobe of the liver. Embryo at the end of week 4.
ver
Um omphalo e te c duct
302
303
25:1
Week 4
4.2.05a Same embryo as in gure 4.2.05.
Week 5
4.2.5a4.2.11 Development of the external form of the liver. Ventral view.
4.2.06
4.2.07
Right and left lobes of the liver. Embryo at the end of week 5.
Week 6
Iv
4.2.08
2 1 4 s 3
Week 7
rv Iv
4.2.09
Embryo at week 7.
2 s
bw
il
304
305
25:1
Week 8
la ra 4. Organs in the Abdomen rv 4.2 The Development of the Liver lv ra rv lv 4.2.11 Embryo late in week 8. 4.2.10 / 11 la 4.2.10 Embryo at week 8.
3 1
2 3
12
306
307
25:1
Week 5
in
4.2.12
Left
Embryo at week 5. The left umbilical vein drains into the sinus venosus via the left common cardinal vein. Ventral-left view.
Week 6
4.2.124.2.14 The left umbilical vein. Lateral/ventralleft view.
Ori ver
4.2.13
Embryo at week 6. The left umbilical vein has lost its connection to the sinus venosus and drains into the liver. Ventral-left view.
la rv lv l
4.2.14
3 2 s il 4 mn
308
309
40:1
Week 6
ricle
4.2.15
Ori
Week 7
Sup
4.2.16
Embryo at week 7.
Pos
liver
310
311
40:1
Week 8
4.2.17 Embryo at week 8.
11
25:1
Week 7
4.2.18 Ramications of the hepatic portal vein are shown. Embryo at week 7.
Mar oop
Week 5
ns
4.2.19
Early arrangements of the hepatic lobules with the branches of the hepatic portal vein and the central veins. Embryo late in week 5.
312
313
200:1
Week 6
4.2.20 Surface area of the right lobe of the liver: hepatic peritoneum and parenchyme of the liver. Embryo at week 6.
Week 7
4.2.21 / 22
4.2.21 Surface area of the right lobe of the liver: hepatic peritoneum and parenchyme and right marginal branch of the portal vein. Embryo at week 7. 4.2.22 Region corresponding to that in gure 4.2.21. Embryo at the end of week 7.
4.2.23
Surface of the venous duct showing the orices of the venae advehentes. Embryo at week 7.
314
315
25:1
Week 5
4.2.24 Embryo at week 5. Lateralright view. The right lobe of the liver has been partly removed to show the hepatic portal vein and its tributary from the subcardinal vein (hepatic portion of the subcardinal vein).
Week 6
R
4.2.25
Subca
duct
Embryo at week 6. Lateral-right view. The right lobe of the liver has been removed to show the subcardinalhepatic anastomosis (communication of the hepatic portion of the subcardinal vein with the hepatic portal vein).
Week 8
4.2.26
Embryo at week 8. The hepatic portion of the inferior caval vein has been established.
ra 13
14
5 6
316
317
318
4.3
319
60:1
Week 5
Sup
4.3.01
Right view of the right superior, inferior, common cardinal, and right umbilical vein. Embryo at week 5.
30:1
4.3.014.3.18 The main blood vessels of the trunk. 4.3.01a Same embryo, same view. The sinus venosus has been opened.
4.3.01, 4.3.02 The early umbilical veins drain into the sinus venosus.
60:1
4.3.02
ein vein in Septum
Same embryo, left view of the left superior, inferior, common cardinal, and the left umbilical vein.
30:1
4.3.02a Same embryo, same view. The sinus venosus has been opened.
320
321
15:1
Week 5
Rig Allan in tery
4.3.03
Week 5 / 6
Me Mese us of
4.3.04
Lateral-left view of the left umbilical artery and vein. Embryo at the end of week 5/early in week 6.
Week 6
ver Inte ry
4.3.05
Ventral view of the left umbilical vein draining into the liver. Embryo at week 6.
Week 5 / 6
wall M
4.3.06
Lateral-left view of the left umbilical artery as it reaches the dorsal body wall. Embryo at the end of week 5/early in week 6.
322
323
15:1
Week 7
ver
4.3.07
Lateral-left view of left umbilical artery as it reaches the dorsal body wall. Embryo at week 7.
ey ery
Week 5 / 6
Remn vein
4.3.08
Remn cut
Ventral view of the left umbilical vein in the body wall. Embryo at the end of week 5/early in week 6.
Week 6
4.3.09
Oric wall
Week 7
4.3.10
Ventral view of the left umbilical vein draining into the liver. Embryo at week 7.
Cut
ment vein
324
325
15:1
Week 6
Subc yme
4.3.11
Embryo at week 6. Lateral-right view. The right lobe of the liver has been removed to show the communication of the hepatic portion of the subcardinal vein with the hepatic portal vein. Embryo at week 8. The supercial portions of the right lobe of the liver have been removed to show the anastomosis of the subcardinal vein with the hepatic veins.
Week 8
4.3.12
Subca ice
4.3.114.3.13 Development of the hepatic portion of the inferior caval vein. Lateral-right view.
L Oric
4.3.13
liver Stomach
Embryo at week 8. The supercial portions of the right lobe of the liver have been removed. The hepatic portion of the inferior caval vein has reached an advanced stage.
326
327
30:1
Week 4
4.3.14 Embryo at the end of week 4. Caudal ventral and left view. The sinus venosus has been opened.
Cran E p
Week 5
Sup Com Inf Rig rdium
4.3.15
4.3.144.3.18 The superior and inferior cardinal veins draining into the sinus venosus via the common cardinal veins.
4.3.16
pha
al vein
Le
Week 6
4.3.17
Trian
mary
328
329
30:1
Week 7
Borde
4.3.18
orn
Embryo at week 7. Lateral-left view. The left common cardinal vein drains into the left sinus horn.
4.3.144.3.18 The superior and inferior cardinal veins draining into the sinus venosus via the common cardinal veins.
330
331
4.4
332
il la lv mn 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
4.4 Abbreviations intestinal loop left atrium left ventricle mesonephros stomach, greater curvature endoderm of the stomach greater omentum lesser omentum spleen peritoneum of the dorsal wall of the omental bursa liver, left lobe bare area of the liver liver, right lobe lung, inferior lobe lung, superior lobe oesophagus gonad genital tubercle duodenum
333
25:1
Week 4
Le Se
4.4.01
l villi
Omp
the
Week 5
Bar Righ In ver
4.4.02
4.4.03
The left lobe of the liver has been removed. Embryo at week 5.
Lef
ein vein
Int
4.4.04
rium n Lef
Week 6
O bud Left
4.4.05
Embryo at week 6.
334
335
25:1
Week 6
la 4. Organs in the Abdomen 4.4 The Development of the Stomach il 1 mn lv 4.4.06 Embryo at week 6.
Week 7 / 8
lv 7
4.4.07 / 08 10 la lv
8 1
11 10 mn
8 7 mn 14 5 1
336
337
25:1
Week 5
Left etal
4.4.09
Embryos at week 5.
rn Left o s
4.4.10
Week 5 / 6
10 4.4.094.4.14 Development of the external form of the stomach. The liver has been removed. Ventral-left view. il mn
4.4.11 / 12
Week 7 / 9
4.4.13 / 14
4 3 15
338
339
25:1
Week 5
4.4.15 The peritoneum and the mesenchyme covering the anterior wall of the stomach have been removed. Ventral view of the basal side of the endoderm of the stomach. Embryo at week 5.
Week 6
4.4.16
4.4.014.4.27 Developmental stages of the stomach. 4.4.17 4.4.154.4.19 Development of the internal form of the stomach. Ventral-left view.
The peritoneum and the mesenchyme covering the anterior wall of the stomach have been removed. Ventral view of the basal side of the endoderm of the stomach. Embryo at week 6.
The ventral wall of the stomach has been removed. Embryo at week 6.
Week 7
4.4.18
The ventral wall of the stomach has been removed. Embryo at week 7.
Week 9
4.4.19
The ventral wall of the stomach has been removed. Embryo at week 9.
340
341
50:1
Week 5
um
4.4.20
Orig m
The origin of the lesser omentum and the omental bursa (lesser sac). Ventral-right view. Embryos at weeks 5 and 6.
Week 6
4.4.014.4.27 Developmental stages of the stomach.
Midd neum oneum
4.4.21
mesenteric vessels
342
343
50:1
Week 6
Parie
4.4.22
al bursa
Ventral-left view of the omental bursa and the pancreas. Except for part of the fundus, the stomach has been removed. Embryo at week 6.
Lateral-left view of the omental bursa and the dorsal mesogastrium. The stomach has been removed. Embryo at week 6.
Week 7
mach
4.4.24
a Supe
Caudal view of the stomach and the omental bursa. The corpus and the pylorus of the stomach have been removed. Embryo at week 7.
4.4.25
Dorsa R al wall
Ventral and caudal view of the stomach, the omental bursa and the pancreas. The corpus of the stomach has been partly and the pylorus completely removed. Embryo at week 7.
344
345
50:1
Week 7
4.4.26 Lateral-left view of the omental bursa and the dorsal mesogastrium. The stomach has been removed. Embryo at week 7.
Dorsa
ecess
4.4.014.4.27 Developmental stages of the stomach. 4.4.27 Ventral and caudal view of the stomach and the omental bursa. The stomach has been partly removed. Embryo at the end of week 7.
12 2 9
13
346
347
348
4.5
The spleen arises in the upper portion of the greater curvature of the stomach (g. 4.5.014.5.03). By the end of week 7 the spleen is demarcated from the wall of the stomach by deepening furrows (g. 4.5.04, 4.5.064.5.10). During the fetal period these furrows will develop into the gastrosplenic and the splenophrenic ligaments. The tail of the pancreas, located in the oor of the omental bursa, approaches the spleen when the recess of the omental bursa is maximally extended towards the left (g. 4.5.05, 4.7.07, 4.7.08).
1 2 3 4 5 6
4.5 Abbreviations spleen stomach, greater curvature greater omentum lesser omentum liver, left lobe gonad
349
30:1
Week 7
obe Reg c
4.5.01
The demarcation of the spleen from the upper pole of the major curvature is not yet visible. Embryo at week 7.
4.5.02
The rst demarcations of the spleen from the upper pole of the major curvature become visible. Embryo at week 7.
4.5.03 5
The demarcated spleen is still completely integrated into the wall of the stomach. Embryo at the end of week 7.
1 2 6
Week 9
1
4.5.04
350
351
30:1
Week 9
4.5.05 Same embryo as in gure 4.5.04. The omental bursa has been opened and the pancreas exposed to show the topographical relationship of the pancreas to the hilus of the spleen.
dy cut
4.5.06
Ventral-left view of the spleen, the stomach and the greater omentum. Embryo at week 9.
352
353
60:1
Week 7
4.5.07 Embryo at week 7.
Week 8
4.5.08
Embryo at week 8.
4.5.074.5.10 Detailed view of the demarcation of the spleen from the wall of the stomach.
Week 9
4.5.09
Embryos at week 9.
4.5.10
354
355
356
4.6
357
50:1
Week 5
4.6.01 Ventral-caudal view of the duodenum and the buds of the bile duct and the ventral pancreas. The peritoneum of the duodenum has been removed. The buds are partly covered by the mesenchyme. Embryo at week 5.
dder creas m
Ventral-caudal view of the duodenum and the bud of the dorsal pancreas. The peritoneum of the duodenum has been removed. Embryo at week 5.
100:1
4.6.02a Same embryo as in gure 4.6.02.
50:1
Week 6
4.6.03 Ventral-caudal view of the pancreas within the mesenchyme of the stomach. Embryo at week 6.
Mese S phros
358
359
50:1
Week 6
4.6.04 Ventral view of the basal endoderm of the stomach, the duodenum, and the buds of the bile duct and the dorsal pancreas. The ventral mesenchyme of the stomach has been removed to show the position of the dorsal pancreas. Embryo at week 6.
phros
ach
Ventral-caudal view of the pancreas within the mesenchyme of the stomach. Embryo at the end of week 6.
4.6.06
Perit hros p
removed
The caudal portion of the opened stomach has been removed to show the omental bursa. The dorsal pancreas within the mesenchyme of the stomach has been exposed. Ventral-caudal view. Embryo at the end of week 6.
Week 7
4.6.07
Cut a
peritoneum
The caudal portion of the opened stomach has been removed to show the omental bursa and its position with respect to the body of the pancreas. The pancreas is now directly beneath the epithelium of the omental bursa. The mesenchyme of the greater curvature of the stomach has been removed. Embryo at week 7.
360
361
50:1
Week 7
4.6.08 Caudal view of the pancreas to show its relation to the omental bursa and the retropancreatic peritoneal recess. Same embryo as in gure 4.6.07.
y wall
Caudal-left view of the primordial radix of the mesentery of the stomach, the cranial border of the retropancreatic peritoneal recess. The stomach has been removed. Embryo at week 7.
Week 8
4.6.10
4.6.11
Duod uct
The peritoneum and the mesenchyme of the duodenum and the ventral portion of the head of the pancreas have been removed to show the origin of the bile duct and the part of the pancreatic head that has developed from the ventral pancreatic bud. Embryo at week 8.
362
363
25:1
Week 9
Stom of the
4.6.12
Caudal view of the stomach and the exposed pancreas. The omental bursa is partly opened. Embryo at week 9.
Cut e eum in
Caudal-left view of the stomach, the spleen, and the exposed pancreas to show the positional relation of the tail of the pancreas to the spleen. The omental bursa is partly opened. Embryo at week 9.
50:1
4.6.14 Details of the secreting lobules of the body of the pancreas. Embryo at week 9.
Week 8
he stomach
4.6.15
creas
Ventral view of the head of the pancreas and the bile duct. The duodenum has been opened. Embryo at week 8.
364
365
50:1
Week 8
mach
4.6.16
pan Du
Ventral view of the exposed endoderm of the duodenum and the bile duct. The head of the pancreas is partly removed. Embryo at week 8.
366
367
Urogenital Organs
369
5. Urogenital Organs
5.15.4
370
chyme that abuts the epithelium of the ureteric bud (g. 5.3.04 5.3.11). The ureteric bud elongates and divides consecutively into up to about 16 branches, which form the pelvis of the kidney, the calyces, and the collecting ducts. Finally, the expanded ends of the collecting ducts (g. 5.3.19) form anchor-like ramications (g. 5.3.205.3.24). The mesenchymal cells in contact with them become arranged as epithelia (g. 5.3.20, 5.3.22) and develop into the urine-producing glomeruli and the urine-concentrating tubular system of the nephron (g. 5.3.23, 5.3.24). The ureter develops from the common outlet of the ureteric bud and the mesonephric duct (g. 5.3.055.3.08). Due to the positional development of the kidney, the ascent to the lumbar level, the ureter elongates considerably (g. 5.3.135.3.16). The urinary bladder arises in the region where the allantoic diverticulum branches o from the end-gut, the urogenital sinus (in the older literature often called cloaca) (g. 5.2.02). The urogenital sinus is separated into urinary bladder and rectum by the urorectal septum (g. 5.2.035.2.09). The free edge of this septum folds up into the urogenital sinus, and in week 6 the separation of the bladder from the rectum is completed (g. 5.2.115.2.14). The most caudal portion of the gut, the postanal gut (g. 5.2.09), remains small and is eventually absorbed. The common orice of the mesonephric duct and the ureter (g. 5.4.035.4.05) becomes duplicated due to the growth of the spur between the mesonephric duct and the ureter (g. 5.4.03, 5.4.05). This spur reaches the lumen of the bladder, thus creating two isolated orices. The exit of the ureter is situated more lateral, whereas the orice of the mesonephric duct is situated more medial (g. 5.4.065.4.09). Due to the growth of the bladder, the exit of the mesonephric duct reaches its position in the proximal portion of the urethra (g. 5.4.09, 5.4.10.)
371
5.1 Abbreviations diaphragm intestinal loop mesonephros right atrium right ventricle mesonephric duct mesonephric vesicle mesonephric glomerulus secretory tubule, orice secretory tubule bare area of the liver right lobe of the liver region of the developing gonad/gonad lung suprarenal gland paramesonephric duct
1 2 3 4 5 6 7 8
5.2 Abbreviations urethra, pelvic part urethra, phallic part urinary bladder anal groove rectum, endoderm peritoneum of the rectum anus mllerian tubercle
372
mn 1 2 3 4 5 6 7 8 9
5.3 Abbreviations mesonephros metanephros ureter mesonephric duct common outlet for meso- and metanephros urinary bladder urethra, pelvic part urethra, phallic part endoderm of the rectum peritoneum of the rectum
373
30:1
Week 4
Lef
5.1.01
phros
Week 5
ver Uroge
5.1.02
5.1.015.1.04 The urogenital fold. 5.1.03 Individual variations of the urogenital fold. Ventral-left views. Embryos at week 5.
5.1.04
374
375
30:1
Week 6
ra 5. Urogenital Organs 5.15.4 The Development of the Urinary Organs 5.1.05 Slight indication of the slit-like demarcation between the mesonephros and the gonad. Lateralright view. Embryo at the end of week 6.
d 7 rv
5.1.055.1.09 The subdivision of the urogenital fold into the mesonephric and the gonadal fold.
Week 7
9 mn 7 8 8
5.1.06 / 07
Due to the recess-like deepening between mesonephros and gonad and the developing recess on the medial side, the gonad achieves a greater free peritoneal surface. The right lobe of the liver has been removed. Ventral views. Embryos at week 7 (5.1.06, 5.1.07) and 8 (5.1.08).
Week 8
5.1.08
376
377
30:1
Week 9
5.1.09 Embryo at week 9. Ventral view. Due to their increase in size the gonads partly overlap the mesonephos.
10
150:1
Week 5 / 7
5.1.10 / 11 5.1.10 Ventral view of the left mesonephros. The mesonephric vesicles and the mesonephric (wolan) duct have been exposed. Embryo at week 5. 5.1.11 Ventral view of the left mesonephros. Some of the mesonephric vesicles and the mesonephric (wolan) duct have been opened. Embryo at week 7.
5.1.055.1.09 The subdivision of the urogenital fold into the mesonephric and the gonadal fold. 5.1.105.1.18 The secretory organs of the mesonephros.
2 1 3 1 4
Week 9
5.1.12
Lateral left view of the left mesonephros. The mesonephric (wolan) duct and the collecting tubules have been exposed. The paramesonephric duct is partly covered by peritoneum. The glomeruli remain hidden. Embryo at week 9.
11
378
379
300:1
Week 6 / 7
5.1.13 / 14 In the opened mesonephric vesicles, the capillary loop of the glomeruli covered by the inner layer of Bowmans capsule is visible. Due to the advancing development of clefts, the originally smooth surface becomes re-arranged into an increasing number of capillary loops. Embryos at week 6 and 7.
Week 5
5 5 2
5.1.17
Surface of a mesonephric vesicle with the outlet of the secretory tubule. Embryo at week 5.
Week 6
5.1.18
An opened mesonephric vesicle shows the capillary loop of the glomerulus and the outlet of the mesonephric tubule. Embryo at the end of week 6.
380
381
60:1
Week 5
5.2.01 Overall view of the position of the urogenital sinus and the urinary bladder. The peritoneal cavity and the urogenital sinus are opened. Ventral and cranial view. Embryo at week 5.
5. Urogenital Organs
Cut
A ened Sa
5.2.02
tube hros Orice
Ventral and left view of the exposed and opened urogenital sinus. Embryo at week 5.
Ur Uro
5.2.03
Left lateral view of the exposed and opened urogenital sinus shows the rst indication of the urorectal septum. Embryo at week 5.
Week 6
5.2.04
Ventral and left view of the exposed and opened urogenital sinus and the urinary bladder. The urorectal septum has developed further. Embryo at week 6.
382
383
60:1
Week 6
5.2.05 / 06 / 07 Cranial view of the opened urinary bladder shows dierent individual developmental stages of the urorectal septum. Embryos at week 6.
5.2.08
Cranial view of the opened urinary bladder. The separation of the anal canal from the urinary bladder is almost complete. Embryo at the end of week 6.
5.2.09
Orice t um m
Lateral-left view of the exposed and opened urogenital sinus, the urinary bladder and the postanal rectum. Embryo at week 6.
Week 7
tum Epit um
5.2.10
Lateral-left view of the external form of the urinary bladder, the urethra and the urogenital sinus. Embryo at week 7.
384
385
60:1
Week 7
End
5.2.11
The anal canal still opens into the urogenital sinus. Lateral-right view. Embryo at week 7.
into
5.2.12
Peri En elium
The separation of the anal canal from the urinary bladder is advanced. Lateral-right view. Embryo at the end of week 7.
5.2.115.2.14 Stages of the development of the perineum. The urinary bladder and the urethra have been opened.
Week 8 / 9
8 6 1
5.2.13 / 14
5.2.13 The separation of the anal canal from the urinary bladder is complete. Lateral-right view. Embryo at week 8. 5.2.14 Embryo at week 9. Lateral-left view.
1 2 2 7 4 5
386
387
100:1
Week 5
5.3.01 Overall left view of the position of the ureteric bud, the mesonephric (wolan) duct, the urogenital sinus, and the urinary bladder. Embryo at week 5.
5. Urogenital Organs
tube
Ur Uro
5.3.02
Urin phros
The epithelium of the ureteric bud, embedded in the metanephric blastema, has been exposed. Embryo at week 5.
200:1
5.3.03 The ureteric bud has been opened. Embryo at week 5.
Lum
stema
388
389
100:1
Week 6
eum Comm
5.3.04
The epithelium of the ureteric bud has been exposed. The ureteric bud, embedded in the metanephric blastema, moves away from the mesonephric duct, thus giving rise to the ureter. Embryo at week 6.
5.3.05
P phros
Comm
Same embryo as in gure 5.3.04. The ureteric bud, the ureter, and the mesonephric duct have been opened.
5.3.06
mn
Lateral-left view of the metanephric blastema enveloping the ureteric bud. The epithelium of the ureter, the mesonephric duct, and the urogenital sinus have been exposed. Embryo at week 6.
5.3.07
hros mes Regi Regi
Same embryo as in gure 5.3.06. The epithelium of the ureteric bud and the mesonephric duct have been exposed.
390
391
100:1
Week 6
5.3.08 Lateral-left view of the opened ureteric bud, the ureter and the mesonephric duct. Due to the elongation in the craniocaudal direction, the ureteric bud becomes kidney-shaped and could be called the pelvis of the future kidney. Embryo at the end of week 6.
calyx Reg ma
Lateral-left view of the exposed epithelium of the pelvis and the ureter. Embryo at the end of week 6.
5.3.015.3.11 Development of the left ureteric bud. Lateral-left view. 5.3.10 Same embryo as in gure 5.3.09. The pelvis has been opened. The ureter is lengthened.
500:1
5.3.11 Detailed view of the contact zone of the pelvis with the metanephric blastema.
392
393
40:1
Week 6
phros
5.3.12
Embryo at week 6.
mes End
5.3.13
eum Comm
5.3.14
Comm
Week 7
Per Co Epi um m
5.3.15
Embryo at week 7.
5.3.16
Epithe ins
394
395
40:1
Week 7 / 9
5.3.17 / 18 Ventral overall view of the kidney. Embryos at weeks 7 and 9.
500:1
Week 7
5.3.19 The contact zone of a collecting duct with the metanephric blastema is shown. Embryo at week 7.
250:1
5.3.20
acture Blo
A fracture through the contact zone of a branch of a collecting duct with the metanephric blastema is shown. Embryo at week 7.
5.3.21
icle Arm , cut icle
396
397
500:1
Week 8
5.3.22 The contact zone of a branch of a collecting duct with the metanephric blastema that will convert into the metanephric epithelium. Embryo at week 8.
250:1
5.3.015.3.24 Developmental stages of the metanephros (kidney). 5.3.23 The metanephric blastema in contact with a branch of a collecting duct has converted into vesicles of metanephric epithelium. Embryo at week 8.
esicle Arms
esicle,
cross section
Week 9
Mesench cle Anc M cle
5.3.24
The branch of a collecting duct and the vesicle of the metanephric epithelium that will make up the nephron. The tubulus system is not yet developed. Embryo at week 9.
398
399
40:1
Week 6
5.4.01 Ventral-left view of the opened urinary bladder and the epithelium of the urethra. Embryo at week 6.
Per
ros of the
Week 7
5.4.02
5.4.01 / 02 Position of the urinary bladder. 5.4.035.4.10 The orices of the mesonephric (wolan) duct and the ureter leading into the urinary bladder.
Epithe um
Lateral-left view of the exposed and opened urinary bladder and the epithelium of the urethra. Embryo at the end of week 7.
Week 6
5.4.03
Peri phros
Com
Ventral-left view of the left ureteric bud, the ureter, the mesonephric duct, and the bladder. Ureter and mesonephric duct have a common excretory duct leading into the bladder. Embryo at week 6.
5.4.04
phros
Comm
Lateral-left view of the orice of the ureter and the mesonephric duct. The common excretory duct is shortened due to elongation of the separating fold between the mesonephric duct and the ureter. Embryo at the end of week 6.
400
401
40:1
Week 7
5.4.05 Ventral-left view of the bladder, the ureter, and the mesonephric duct. The orice of the ureter has achieved a more lateral position than the opening of the mesonephric duct. Embryo at week 7.
phros
5. Urogenital Organs
End
200:1
5.4.06 5.4.015.4.10 Development of the urinary pathways. Detailed view of the opened urinary bladder. The left ureter and the left mesonephric duct have achieved two separate orices. Embryo at the end of week 7.
Epit
duct
5.4.035.4.10 The orices of the mesonephric (wolan) duct and the ureter leading into the urinary bladder.
120:1
Week 8
5.4.07 Ventral-right view of the bladder. Orices of the mesonephric ducts, the orice of the left ureter is marked by a circle. Embryo at week 8.
20:1
Week 9
5.4.08 Ventral-right overall view of the opened bladder, the urethra, and the orice of the right ureter. Embryo at week 9.
Uri
M a mesonephric ducts
art
402
403
40:1
Week 9
5.4.09 Detailed view of the same embryo as in gure 5.4.08. The lateral position of the orice of the ureter and the medial position of the orice of the mesonephric duct on the mllerian tubercle are clearly seen.
ter
5.4.10
ter
5.4.035.4.10 The orices of the mesonephric (wolan) duct and the ureter leading into the urinary bladder.
Detailed ventral and cranial view of the same embryo as in gure 5.4.09. The dierent positions of the orices of the ureter and of the mesonephric duct are obvious.
404
405
5. Urogenital Organs
406
5.5
mn 1 2 3 4 5 6 7
5.5 Abbreviations mesonephros ovary uterine tube round ligament testis gubernaculum testis rectum suprarenal gland
407
20:1
Week 6
Ba Intest
5.5.01
5. Urogenital Organs
wall
Week 7
Cut
obe ver
5.5.02
Ventral-right view of the advancing demarcation of the right gonad from the mesonephros. Dierent developmental stages of embryos at week 7 (5.5.025.5.04) and 8 (5.5.05).
5.5.03
Righ ver vein
5.5.04
obe Me ver
Week 8
and
5.5.05
Me
408
409
20:1
Week 9
7 5. Urogenital Organs 5.5 The Development of the Gonads 5.5.06 Ventral view of the testes.
mn 5
5.5.065.5.10 First outwardly visible dierences between ovary and testis. Embryos at week 9.
5.5.07 7
1 2 3 6
200:1
5.5.08 / 09 Individual dierences in the surface arrangement of the peritoneum of the ovaries.
5.5.10
Unlike the ovary, the peritoneum of the testis has a soft surface.
410
411
5. Urogenital Organs
412
5.6
413
80:1
Week 7
Pa ct
5.6.01
Ventral-right view of the median part of the right mesonephros. The epithelia of the mesonephric (wolan) and paramesonephric (mllerian) ducts have been exposed. Embryo at week 7.
200:1
5.6.01a Same embryo as in gure 5.6.01, same view.
80:1
Week 8
Peritoneum of the mesonephros Mesonephric (wolan) duct Secretory tubule Mesenchyme of the mesonephros Peritoneum of the gonad Paramesonephric (mllerian) duct Cut area of the gonad Mesonephric vesicle
5.6.02
Ventral-right view of the caudal part of the right mesonephros. The epithelia of the mesonephric duct, the secretory tubules and the paramesonephric duct have been exposed. The mesonephric and the paramesonephric ducts have been cut. The paramesonephric duct has crossed over the mesonephric duct. Embryo at week 8.
414
415
20:1
Week 8
Uteri
5.6.03
nds
Ventral view of the position of the ovaries and the uterine tubes. Embryo at week 8.
Week 9
5.6.015.6.11 The reproductive pathways.
Uteri
5.6.04
Ventral view of the right ovary with the mesovarium, the uterine tube and uterus, and the round ligament. Embryo at week 9.
ndus
5.6.05
ucts M
Ventral view of the exposed left paramesonephric (mllerian) duct crossing the mesonephric (wolan) duct. The fused paramesonephric ducts (the uterus) reach the sinusal tubercle (mllerian tubercle). Embryo at week 9.
5.6.06
Peritoneum of the mesonephros Mesonephric duct Fused paramesonephric ducts Mllerian tubercle Orice of the mesonephric duct
Detailed ventral view of the exposed uterus and the mesonephric ducts (Gartners duct). Embryo at week 9.
416
417
80:1
Week 7
5.6.07 Cranial view of the abdominal ostium of the right paramesonephric (mllerian) duct, now termed the uterine tube. Embryo at week 7.
Week 9
5.6.08
Cranial view of the abdominal ostium of the right paramesonephric (mllerian) duct. Embryo at week 9.
20:1
5.6.015.6.08 The female genital pathways. 5.6.095.6.11 The male genital pathways.
M
5.6.09
Ventral view of the testes and the mesonephric duct (ductus deferens). Embryo at week 9.
Me
40:1
5.6.10 Same embryo as in gure 5.6.09. Dorsal and cranial view of the exposed epithelia of the mesonephric ducts (ductus deferentes) and the regressing fused paramesonephric ducts.
80:1
5.6.11 Same embryo as in gure 5.6.09. Detailed view of the orices of the ductus deferentes.
Mes phric
418
419
421
6.1
422
Inside the lateral ventricle, the basal ganglia develop at its base (g. 6.1.39, 6.1.496.1.53, 6.1.65). At the superior medial wall of the lateral ventricle, the choroid plexus is folded inward (g. 6.1.39, 6.1.616.1.65). At the base of the fourth ventricle the bulges of the rhombomeres are formed (g. 6.1.546.1.57).
The Origin of the Hypophysis (g. 6.1.666.1.73) The endodermal component of the hypophysis, the adenohypophysis, is an evagination of the roof of the early oral cavity (g. 6.1.666.1.69). The adenohypophysial pouch is in close contact with the oor of the diencephalon (g. 6.1.68) where the neurohypophysial diverticulum arises (g. 6.1.73). The origin of the adenohypophysial pouch is narrowed (g. 6.1.706.1.72) and eventually loses its connection with the epithelium of the oral cavity.
di I m p rh t 1 2 3 4 5 6 8 9 11 12 13 15 17
6.1 Abbreviations diencephalon pharyngeal arch I mesencephalon prosencephalon rhombencephalon telencephalon optic vesicle optic cup optic stalk orice of Rathkes pouch site of the lamina terminalis trigeminal ganglion hypothalamus basal ganglia retina mesencephalic exure olfactory diverticulum otic vesicle vagal nerve
423
60:1
Week 4
Lume the ore
6.1.01
hI
6.1.02
opore Op
At the site of closure of the cranial neuropore, the ectoderm is still in contact with the brain. Embryo in the middle of week 4.
6.1.016.1.34 Developmental stages of the external form of the brain. 6.1.03 6.1.016.1.11 Ventral view of the brain. m The optic vesicle has emerged. Embryo at the end of week 4.
Week 5
6.1.04 / 05
Embryos at week 5.
1 3 di 4
424
425
60:1
Week 5
m 6. Brain and Sensory Organs t 6.1 The Development of the Brain di 4 6.1.016.1.34 Developmental stages of the external form of the brain. 3 2 6.1.06 Embryo at week 5.
Week 6
6.1.016.1.11 Ventral view of the brain.
6.1.07
Embryo at week 6.
2 3 5 di
426
427
30:1
Week 6
6.1.07a Same embryo as in gure 6.1.07.
6.1.016.1.34 Developmental stages of the external form of the brain. t t 6.1.016.1.11 Ventral view of the brain. 2 2
6.1.08 / 09
di
3 l
5 4
Week 7
6.1.10
Embryo at week 7.
3 4
428
429
30:1
Week 8
6.1.11 Embryo at week 8.
13
6.1.016.1.11 Ventral view of the brain. 6.1.126.1.21 Cranial view of the brain.
60:1
Week 4
pore
6.1.12
Me
6.1.13 p
m rh
430
431
60:1
Week 5
6.1.14 / 15 Embryos at week 5.
Week 5 / 6
6.1.16 / 17
432
433
30:1
Week 6
6.1.17a Same embryo as in gure 6.1.17
Week 7 / 8
6.1.20 / 21
434
435
60:1
Week 4
M on
6.1.22
Rho
Week 5
6.1.016.1.34 Developmental stages of the external form of the brain. m
6.1.23 / 24
Embryos at week 5.
rh 1 t
436
437
60:1
Week 5
6.1.25 Embryo at week 5.
17
15
12
438
439
30:1
Week 5
6.1.25a Same embryo as in gure 6.1.25.
Week 6
6.1.26
Embryo at week 6.
Week 7
6.1.27
Embryo at week 7.
di
440
441
15:1
Week 7
6.1.27a Same embryo as in gure 6.1.27.
Week 8
6.1.28
Embryo at week 8.
Week 9
6.1.29
Embryo at week 9.
442
443
30:1
Week 5
6.1.30 / 31 Embryos at week 5.
Week 6
6.1.016.1.34 Developmental stages of the external form of the brain.
6.1.32 / 33
Embryos at week 6.
Week 7
6.1.34
Embryo at week 7.
444
445
60:1
Week 4
Ventr
6.1.35
Ventral view into the optic vesicles and the prosencephalon. Embryo in the middle of week 4.
ium
6.1.36
on Op on
Ventral view into the optic vesicles and the prosencephalon. Embryo at the end of week 4.
Week 5
6.1.356.1.39 Ventral view into the opened brain.
ricle
6.1.37
Ventral view into the optic vesicles, the diencephalon and the mesencephalon. Embryo at week 5.
Die
446
447
30:1
Week 5
6.1.37a Same embryo as in gure 6.1.37.
Week 7 / 8
6.1.356.1.57 Developmental stages of the internal form of the brain.
6.1.38 / 39
6.1.38 Ventral view into the cerebral hemispheres. Embryo at week 7. 6.1.39 Ventral view into the cerebral hemispheres. Embryo at week 8.
448
449
60:1
Week 4
Sur Cu icle alon,
6.1.40
Cranial view into the optic vesicles and the prosencephalon. Embryo in the middle of week 4.
6.1.41
Cranial view into the optic vesicles and the prosencephalon. Embryo at the end of week 4.
alon
Week 6
6.1.42
3 11 8
450
451
15:1
Week 6
6.1.42a Same embryo as in gure 6.1.42.
Week 6 / 8
t t
6.1.43 / 44
6.1.43 Cranial view into the cerebral hemispheres, the diencephalon, and the mesencephalon. Embryo at the end of week 6. 6.1.44 Cranial view into the cerebral hemispheres, the diencephalon, and the mesencephalon. Embryo at week 8.
12
12
452
453
15:1
Week 5
e Inva talk
6.1.45
Lateral-right view into the left cerebral hemisphere, the diencephalon, and the mesencephalon. Embryo at week 5.
Week 6
Mes e talk
6.1.46
Lateral-right view into the left cerebral hemisphere, the diencephalon, and the mesencephalon. Embryo at week 6.
6.1.356.1.57 Developmental stages of the internal form of the brain. 6.1.47 6.1.456.1.49 Lateral-right view into the opened brain.
Me here k
Lateral-right view into the left cerebral hemisphere and the diencephalon. Embryo at the end of week 6.
Week 7
Me c here
6.1.48
6.1.49
here T Tem Ba
454
455
15:1
Week 8
ping
6.1.50
R pos
Lateral-right view of dierent developmental stages of the internal arrangement of the right cerebral hemisphere. Embryos at week 8.
6.1.51
6.1.52
6.1.53
456
457
30:1
Week 5
ping
6.1.54
Embryos at week 5.
Rh
erve
6.1.55
6.1.546.1.57 Dorsal and cranial view into the oor of the rhombencephalon. The roof of the hindbrain has been removed to show the rhombomeres.
Week 6
6.1.56 / 57
Embryos at week 6.
458
459
15:1
Week 5
dage V Va
6.1.58
Embryo at week 5.
ve
Week 6
Facial nerve on endo lary, s ce
6.1.59
Embryos at week 6.
Gl
6.1.60
ar
V Vagal nerve
Glossopharyngeal nerve
460
461
30:1
Week 8 / 9
6.1.61 Lateral-left view of dierent developmental stages of the choroid plexus in the left lateral ventricle. Embryos at weeks 8 and 9.
6.1.62 / 63
6.1.64 / 65
462
463
30:1
Week 5
6.1.66 Ventral view of the oral cavity showing the orice of the adenohypophysial (Rathkes) pouch. Embryo at week 5.
ch
60:1
6.1.666.1.73 The hypophysis.
Week 6
6.1.67
halon Endo
Ventral-right view of the exposed adenohypophysial pouch and its contact region with the anlage region of the neurohypophysis. Embryo at week 6.
30:1
Week 7
6.1.68 Overall view of the position of the adenohypophysis and neurohypophysis. The right eye with the optic stalk and the right cerebral hemisphere have been removed. Embryo at week 7.
6.1.69
Same embryo as in gure 6.1.68. Ventral view of the adenohypophysial pouch. The diencephalon has been removed.
464
465
60:1
Week 7
6.1.70 / 71 The caudal view of the oral cavity shows dierent individual examples of the phase of the orice of Rathkes pouch losing the connection with the roof of the mouth. Embryos at week 7.
6.1.72
6.1.73
Cranial view of the oor of the diencephalon showing the anlage region of the neurohypophysis. Embryo at week 7.
466
467
6.2
468
m p 1 3 4 5 6 7
6.2 Abbreviations mesencephalon prosencephalon optic vesicle retina pigmented epithelium lens optic stalk, optic nerve retinal (choroid) ssure
469
100:1
Week 4
6.2.01 Ventral views of the prosencephalon and the optic vesicles, external and internal aspects. Embryo in the middle of week 4.
opore Ec
Op
elium
6.2.03
lon Me
Lateral-right view of the right optic vesicle. Embryo in the middle of week 4.
470
471
100:1
Week 4
6.2.04 / 05 Ventral-cranial views of the prosencephalon and the optic vesicles, external and internal aspects. Embryo at the end of week 4.
6.2.06
Ventral-cranial view of the opened prosencephalon and the optic vesicles. Early transformation of the optic vesicle into the optic cup. More advanced stage of an embryo at the end of week 4.
1 6
472
473
100:1
Week 5
6.2.07 Early invagination of the retinal disc, external and internal views. Embryos at week 5.
up
6.2.076.2.14 Formation of the optic cup. Ventral-left views of the right eye. The overlying ectoderm with the anlage of the lens has been removed. 6.2.09 Advanced stage of invagination, origin of the retinal ssure. Embryo in the middle of week 5.
6.2.10
ium
Cho
474
475
100:1
Week 5
6.2.11 Embryo in the middle of week 5.
S Ch men
Week 6
r s
6.2.12
Embryo at week 6.
6.2.076.2.14 Formation of the optic cup. Ventral-left views of the right eye. The overlying ectoderm with the anlage of the lens has been removed.
ure
Week 5
ium
6.2.13
The pigmented layer of the optic cup has been partly removed and the optic stalk, the future optic nerve, has been opened. Embryo at week 5.
Week 6
elium Ch
6.2.14
The pigmented layer has partly been removed to show the retinal (chorioid) ssure. Embryo at week 6.
476
477
100:1
Week 5
sicle
6.2.15
Le
The optic cup has been opened to show the retinal disc (placode) in contact with the lens disc (placode). Embryo at week 5.
face
Early invagination of the lens disc to form the lens vesicle. Embryo at week 5.
6.2.17
6.2.18
Ec
The optic cup has been exposed to show the position of the lens ectoderm. Embryo at week 5.
ve
478
479
100:1
Week 5
6.2.19 The pigmented layer has been removed. Advanced stage of invagination of the lens. Ventral-left view of the right eye. Embryo at week 5.
Week 6
6.2.016.2.33 Developmental stages of the eye.
6.2.20
The retina and the pigmented layer have been partly removed. The lens vesicle has been opened. Embryo at week 6.
200:1
Week 7 / 8
6.2.21 / 22 6.2.21 The lens pit is closed and forms the lens vesicle. Cranial view of the opened vesicle. Embryo at week 7. 6.2.22 The lens vesicle has been opened near its cranial pole. The lumen of the lens vesicle is narrowed due to the thickening of the posterior lens epithelium. Embryo at week 8.
Week 8
6.2.23 / 24
6.2.23 Same embryo as in gure 6.2.22. The cross-fracture of the lens vesicle at its equator shows the primary lens bres. 6.2.24 The lens vesicle has been opened near its cranial pole. Due to the elongation of the lens bres the lumen of the lens vesicle has become slit-like. Embryo at the end of week 8.
480
481
800:1
Week 6 / 8
6.2.25 / 26 6.2.25 Longitudinal fracture of the primary lens bres. Embryo at week 6. 6.2.26 Longitudinal fracture of the primary lens bres. Embryo at week 8.
Week 9
6.2.016.2.33 Developmental stages of the eye.
6.2.27 / 28
6.2.27 Longitudinal fracture of the primary lens bres. Embryo at week 9. 6.2.28 The longitudinal fracture of the primary lens bres at the level of the equator shows the row of nuclei of the lens bres. Embryo at week 9.
100:1
Week 6
edge
6.2.29
Sagittal fracture of the retina and the pigmented epithelium shows the position of the lens. Lateral-left view. Embryo at week 6.
482
483
100:1
Week 6
6.2.30 Frontal view of the eye cup and the lens. Embryo at the end of week 6.
5 7
Week 6 / 7
4 3 6 4 3 5 6
6.2.31 / 32
Week 8
6.2.33
484
485
6.3
486
1 2 3 4
487
25:1
Week 4
ld P
6.3.01
6. Brain and Sensory Organs 6.3 The Middle and the Internal Ear
Cut
6.3.02
150:1
6.3.03 Cross-fraction of a more advanced otic pit closing to form the otic vesicle. Embryo at week 4.
25:1
Week 5
6.3.04 Position of the otic vesicle with an indication of the endolymphatic diverticulum. Lateral-right view. Embryo at week 5.
Man
erves
y g
nd IV
6.3.05
Floor En on vein
Lateral-right view of the opened otic vesicle and the endolymphatic diverticulum. Embryo at week 5.
488
489
25:1
Week 5
Base halon
6.3.06
Cranial view of the oor of the rhombencephalon and the otic vesicles. Embryo at week 5.
6. Brain and Sensory Organs 6.3 The Middle and the Internal Ear
30:1
Week 8
6.3.07
Ante ct
duct
6.3.08
Ante
Cranial view of the right vestibular apparatus of a more advanced stage. Embryo at week 8.
duct
6.3.09
An Ori ct
duct
6.3.10
Post eatus
490
491
30:1
Week 8
Ant
6.3.11
Lateral view. Same embryo as in gure 6.3.10. The utricle has been opened.
duct
6. Brain and Sensory Organs 6.3 The Middle and the Internal Ear
Post
ct
6.3.12
l r duct
Ventral-left view of the position of the exposed and partly opened left vestibular apparatus and the cochlear duct. Embryo at week 8.
Pha
6.3.016.3.19 The inner ear. 6.3.076.3.19 Dierent views of the exposed vestibular apparatus.
Week 9
Ante
6.3.13
duct
Lateral-left view of the right vestibular apparatus and the cochlear duct. The vestibule, the saccule, and the cochlear duct have been opened. Embryo at week 9.
492
493
30:1
Week 9
6.3.14 Same embryo as in gure 6.3.13. Dorsalcranial view of the right vestibular apparatus and the cochlear duct shows the position of the posterior semicircular duct.
6. Brain and Sensory Organs 6.3 The Middle and the Internal Ear
End
uct uct
Week 8
6.3.15
Dorsal-left view of the right vestibular apparatus and the cochlear duct. The saccule and the cochlear duct have been opened. Embryo at week 8.
duct
6.3.016.3.19 The inner ear. 6.3.076.3.19 Dierent views of the exposed vestibular apparatus.
Post
6.3.16
Saccule Ante
Lateral-left view of the right vestibular apparatus and the cochlear duct. The utricle and the cochlear duct have been opened. Embryo at week 8.
Lat duct
6.3.17
moved sem
Ventral-left view of the right vestibular apparatus and the cochlear duct. The saccule, the utricle, and the ampullae of the anterior semicircular duct have been opened. The posterior semicircular duct has been partly removed. Embryo at week 8.
494
495
250:1
Week 8
6.3.18 Detailed view of an ampullary crest.
6. Brain and Sensory Organs 6.3 The Middle and the Internal Ear
6.3.19 6.3.016.3.24 Developmental stages of the inner and the middle ear.
6.3.016.3.19 The inner ear. 6.3.076.3.19 Dierent views of the exposed vestibular apparatus. 6.3.206.3.24 The middle ear.
25:1
Week 6
y
6.3.20
Ventral view of the exposed and opened tympanic cavities. Embryo at week 6.
50:1
Week 8
6.3.21 Ventral view of the opened right tympanic cavity. Same embryo as in gure 6.3.07.
496
497
50:1
Week 7
6.3.22 Ventral view of the opened right tympanic cavity with prominence of the malleus. Embryo at week 7.
6. Brain and Sensory Organs 6.3 The Middle and the Internal Ear
25:1
Week 8
1 6.3.23 Ventral view of the pharynx showing the origin of the pharyngotympanic (auditory) tube. Embryo at week 8.
6.3.24
Ventral-left view of the position of the pharyngotympanic (auditory) tube. Embryo at week 8.
be
Lo
498
499
500
6.4
501
50:1
Week 4
6.4.01 The closure of the caudal neuropore. Lateral and lateral-caudal views of the caudal region of embryos at week 4.
6.4.02
75:1
6.4.04 Cross-fractures of embryos at the lumbar level. Embryos at week 4 and 5.
Inte
Week 5
6.4.05
Meso tube
502
503
20:1
Week 7
6.4.06 Lateral right views of the exposed spinal ganglia. Embryos at week 7.
40:1
6.4.016.4.10 The spinal cord. 6.4.07
504
505
Index
Allantoic diverticulum
Anus 1.6.23/24, 5.2.14 anal groove 1.6.04/11/16/21/22, 5.2.12/13 anal pit 1.6.16/2126 anal tubercle 1.6.04/11/16/21/22/25/26, 4.1.10 Artery(ies) aorta, abdominal 6.4.04/05 aortic arch 3.1.22/7073/83/84 aortic duct 3.1.7073, 3.1.81 ascending 2.5.12, 3.1.22/23/26/29/39/40/52/64/70/73/79/83/84, 4.3.13 carotic duct 3.1.86 descending 1.4.38, 2.4.12, 3.1.7073/86/91 paired 2.1.02/11/12, 2.4.13/14, 2.5.06/07, 2.6.01/02, 3.1.69/8890 aortic sac 2.4.13/14, 3.1.42/43, 3.1.7478, 3.1.87/8890 basilar 6.1.46 brachiocephalic 3.1.71/73/83/84/89 carotic 3.1.71/73/76/78/86 coronary 3.1.24/29 mesenteric superior 4.1.10, 4.4.21/24 pharyngeal arch 2.4.1214, 2.5.06/12, 2.6.02/03, 3.1.42/43/69/74, 3.1.7582, 3.1.8591, 6.3.04 pulmonary 2.6.02, 3.1.69/7173/81/82 pulmonary trunk 3.1.22/23/26/27/29/41/52/63/70/73/84 subclavian 3.1.73 umbilical 1.5.20/23/25/27/30, 1.6.04/09, 4.1.10, 4.2.26, 4.3.0308, 5.1.09, 5.2.01, 5.3.01/12
Brain 1.2.02/10/22, 6.1.0173 basal ganglia 6.1.39/4953/64 cerebellar plate 6.1.43/54, 6.3.06 choroid plexus 6.1.39/5053, 6.1.6165
506
diencephalon
epiphysis form external 6.1.0134 internal 6.1.3557, 6.1.6163/65, 6.2.05 hypothalamus 6.1.68 lamina terminalis 6.1.06/09 mesencephalic exure 6.1.25/43/44/46/60 mesencephalon 1.2.03/05/09/10/11/22, 1.3.21, 6.1.03/06/12, 6.1.1325 6.1.27/28/3033/3538/40/41/4547/60, 6.2.03/04/06 neurohypophysis 6.1.73 olfactory diverticulum 6.1.11 prosencephalon 1.2.0103/05/18, 1.3.23, 4.1.03, 4.2.02, 6.1.03/04/12/14/ 15/22/35/36/40, 6.2.03/04 rhombencephalon 1.1.0409, 1.1.11, 1.3.18/21, 6.1.03/22/23/25, 6.1.5457, 6.1.60, 6.3.05/06 telencephalon 1.2.09/11/21, 6.1.0508, 6.1.10/11, 6.1.1621, 6.1.2325/ 2729/43/44/47/60, 6.1.33/34 cerebral hemisphere 2.2.10/23, 6.1.0711/1721/2629/33/34/38/ 39/4349 thalamus 6.1.42/43 ventricle 6.1.3740, 6.1.4257, 6.1.50
Chorion
1.1.01
Diaphragm
1.4.24, 3.2.15/22/23/27/32/55/63, 4.1.01/02, 4.2.01/02/05/14/18, 4.3.02/09/15, 4.4.01/04/05/10/08/10, 5.1.05 Ductus arteriosus, see Aortic duct
Ear external 1.2.12/13/1517/25/28/29/3437, 1.3.22/3335/42, 1.3.3661 internal 6.3.0119, 2.4.04 cochlear duct 2.4.04, 6.3.08/09/1116 endolymphatic appendage 6.1.5860, 6.3.05 endolymphatic duct 6.3.0711/14 otic cyst 6.3.0406
507
Ear (continued) internal (continued) otic pit 1.1.02, 1.3.0103/36/37, 6.3.01/02 otic vesicle 1.2.30, 6.1.25/5860, 6.3.03 saccule 6.3.13/15/17 semicircular duct 6.3.0717 ampulla 6.3.1215/1719 crus commune 6.3.0814/16 utricle 6.3.0717 middle auditory tube 2.2.22/29/30, 2.4.03/04, 6.3.12/23/24 pharyngo-tympanic tube, see Auditory tube tympanic cavity 6.3.2022 Embryo, form, external 1.1.0113 Eye 1.1.03/04/05/08/09, 1.2.11/12/1417/20/21/2329/3337, 1.3.08/21/3335, 2.2.09, 2.3.02, 6.2.0133 choroid ssure 6.1.09/26, 6.2.08/1012/14/29/30 lens 6.1.26/48, 6.2.1012/15/16/1820/2933 bres 6.1.2128 pit 1.1.06/07, 1.2.20/21/32, 1.3.12/18/26, 2.2.01/04, 6.1.25, 6.2.1720 placode 6.2.16 optic cup 6.1.06/07/10/1719/33/34/38, 6.2./09/11/12/1820 optic stalk /nerve 6.1.0508/10/14/22/26/33/34/3638/42/4548/60, 6.2.07/08/1013/16/18/29/31/32 optic ventricle 6.1.01/35/37, 6.2.02 optic vesicle 6.1.0205/12/15/16/22/35/36/40/41, 6.2.03/04/06/07/15/16 pigmented epithelium 6.2.08/10/13/14/29/3133 position 1.2.14/16/17/24/26/27/29/3337, 1.3.07/13/15/3335, 2.2.09 retina 6.1.37/42, 6.2.08/10/13/14/29/3133 retinal disc 6.2.15
Face
1.2.0137
Gallbladder 3.2.60, 4.2.24/26, 4.6.01, 4.2.25 Ganglion, spinal 6.4.05/06/07 Genitalia, external 1.5.2629, 1.6.0122, 4.1.10/16/18, 4.2.11, 4.3.07/10, 4.4.07, 5.2.09, 5.4.07 genital swelling 1.6.1722
508
genital tubercle 1.5.2629, 1.6.0216 Glands adenohypophysis 1.2.04, 2.2.24, 2.3.02/03, 2.4.01, 6.1.05/06/09/10/46, 6.1.6671 parathyroid 2.5.12, 2.6.01, 2.6.03 parotic 2.1.36 sublingual/submandibular 2.1.37 suprarenal 5.1.08/09, 5.5.05/06/07, 5.6.03 thyroid 2.1.33/34/35 Gonads 4.3.13, 4.4.27, 4.5.03, 5.1.0509, 5.5.0110, 5.6.03/04/09 ovary 5.5.0709, 5.6.03/04 testis 5.5.06/10, 5.6.09 Gut 1.5.20/27, 3.2.22, 4.1.0119, 4.2.0406/12, 4.3.12/15, 4.4.0204, 5.1.0104, 5.2.01, 5.3.01, 6.4.05 caecum 4.2.18 duodenum 3.2.21/60, 4.2.17/24/25, 4.3.17, 4.4.14/2022, 4.5.05, 4.6.01/ 02/04/06/1013/15/16, 5.5.03/04 foregut 3.2.01/02/03 hindgut 4.1.05 intestinal loop 1.5.28, 3.2.31, 4.1.0619, 4.2.09/1315/18/24/25, 4.3.0611, 4.4.07, 5.1.05/06, 5.5.01 intestinal port caudal 4.1.01/04, 4.2.01 cranial 3.1.04, 3.2.01/56, 4.1.01/02/04, 4.2.01/02/04, 4.3.14 intestinal tube 4.1.0609, 5.1.0104 mesentery 1.5.27, 4.3.04/06, 4.4.02, 5.6.03, 6.4.05 omphalo-enteric duct 4.1.04/05, 4.2.05, 4.3.05/14/17, 4.4.01, 5.5.01 postanal 5.2.09 rectum 5.2.0204/0914, 5.3.01/06/1216, 5.4.01/02/04/05, 5.5.07, 5.6.0305/09
Heart 3.1.0180 coronary sinus 3.1.45/53/56, 3.2.19 form, external 3.1.0129, 3.2.22/23/55, 4.1.02 infundibulum aortic 3.1.41/59/60 pulmonary 3.1.39/40 outow tract aortic 3.1.43/62
509
Heart (continued) outow tract (continued) pulmonary 3.1.43/44/62 pulmonary ridges 3.1.45 septation aortico-pulmonary septum 3.1.4244/80 atrio-ventricular cushions 3.1.3032/3538/40/51/52/57/61/62 conus 3.1.33/34 conus septum 3.1.3538/61/62 interatrial septum 3.1.31, 3.1.4553, 3.1.57, 4.3.17/18 interventricular septum 3.1.3741/57/61/62 sinus septum 3.1.53 truncus septum 3.1.35/37/44/77 sinus horn 3.1.52, 3.2.22/23/29/31/34/62, 3.2.19/29/36, 4.3.18, 4.4.0406/11 sinus venosus 3.1.01/04/15/46, 3.2.57, 4.1.03, 4.3.01/02/14/15, 4.4.01 supraventricular crest 3.1.63 valves mitral 3.1.3032/35/37, 3.1.5760 pulmonary semilunar 3.1.3540/64, 3.1.6568 sinus 3.1.45 tricuspid 3.1.3032/3638/40/51, 3.1.6164 venous 3.1.53/55/56, 4.3.17 ventricular loop 3.1.01/02/03/04/05/06, 3.2.55, 4.1.02/03, 42.02, 4.3.14 Hypophysis adenohypophysis, see Glands neurohypophysis, see Brain
Jaw lower 1.1.0212, 1.2.0137, 1.3.2832/34/35, 2.1.0125, 2.2.09/22, 6.3.24 upper 1.2.1217/2729/37, 1.3.3335, 2.2.26/31, 2.3.13 maxilla 1.2.15, 2.2.24, 2.3.04/05 maxillary eminence 1.1.0312, 1.2.0310, 1.2.1928, 1.2.3136, 1.3.0422, 1.3.31/32/38/4248, 2.2.01/02/05/ 06/08/12, 2.3.03, 6.1.14/45
510
Larynx 1.4.40, 2.5.0113, 2.6.03 arytenoid swelling 2.1.26 laryngo-tracheal groove 2.1.01/02/04/11/24, 2.4.0710/12/ 13, 2.5.0507/0911, 3.1.8789/91 Limb lower 1.5.0130 foot 1.5.0813, 1.5.22, 1.6.08, 4.2.11, 4.3.10 heel 1.5.11/13/22 lower leg 1.5.09/20/22/30, 1.6.08 thigh 1.5.08/09/1922, 1.6.08 toe 1.5.1013 upper 1.3.19/20, 1.4.0140 apical ectodermal ridge 1.4.2326 elbow region 1.4.13/39 nger 1.4.11/12/14/1619/27/28 forearm 1.4.11/13/33/39 hand 1.4.0811/1319/25/27/28/39 shoulder region 1.4.10/32/33/36/39 upper arm 1.4.26/27/33/36/39 Liver 3.2.17/19/22/23/26/28, 4.2.0126 bile duct 4.6.02/04/15/16 caudate lobe 4.4.21/25, 4.6.07 ductus venosus 3.2.21, 4.2.15/17/23/25/26, 4.3.12/13 falciform ligament 1.5.30, 4.3.10 form, external 4.2.0511 hepatic diverticulum 3.1.04, 4.1.02, 4.2.0104 hepatic duct 4.2.25 structure 4.2.2022 triangular ligament 3.1.55/56, 3.2.17/19/28/30, 3.2.19, 4.3.17/18 veins 4.2.1526 Lung 3.2.0163 bronchus 3.2.08/09/11/12/49/51 form, external 3.2.3348 lobar bronchi 3.2.4954 lobar bud 3.2.0912 lung bud 2.5.0104, 3.2.0107, 3.2.1318, 3.2.2227, 3.2.33/34, 3.2.5762, 4.4.03/04/05/09 pericardio-peritoneal canal 3.2.04/07, 3.2.5659 pleural cavity 3.2.61/62 pleuro-peritoneal canal 3.2.14/16/33/6063
511
Mandible, see Jaw, lower Maxilla, see Jaw, upper Mediastinum 3.2.07/59, 4.4.20 Mesonephros 5.1.0118 form, external, position 1.5.26, 1.6.05, 3.1.55, 3.2.16/19/22/25/27/60, 4.1.0609/1113/15, 4.2.15/24/25, 4.3.11/13/17, 4.4.12/21/27, 5.1.0109, 5.5.0107 mesonephric duct 5.1.1012, 5.2.02/04/09, 5.3.01/02/0407/09/10/ 1215, 5.4.01/02/04/06/07/09, 5.6.01/02/05/06/ 0911, 6.4.05 mesonephric glomerulus 5.1.11, 5.1.1318, 6.4.05 urinary pole 5.1.18 mesonephric vesicle 5.1.10/17/18 paramesonephric duct 5.1.12, 5.4.08, 5.6.01/02/04/05/10/11 secretory tubule 5.1.1012, 5.1.17, 5.6.02 urogenital ridge 5.1.0104, 5.5.01 Metanephros 5.3.0124 calyx, primary 5.3.04/0710/13 collecting duct 5.3.1924 common outlet for meso- and metanephros 5.3.05/06/08/10/12/14/ 15, 5.4.04 metanephric blastema 5.3.0111, 5.3.13/1922 metanephric vesicle 5.3.17/18/21/23/24 pelvis 5.3.05/0710/13/17/18 position 4.1.16, 4.3.07, 5.3.12/1416 ureter 5.3.0410/1216, 5.4.0409 ureteric bud 5.3.0108, 5.3.11 Mouth 1.2.0117, 1.2.27, 1.3.2426/29/31, 2.2.09, 6.1.03
Nerve facial 6.1.5860, 6.3.0406 glossopharyngeal 6.1.25/54/5860, 6.3.0406 spinal 6.4.04/0608 trigeminal 6.1.25
512
ganglion 6.1.23/24/54/58/59, 6.3.05 mandibular 6.1.59/60, 6.3.04 maxillary 6.1.59/60, 6.3.04 nasal 2.2.27 ophthalmic 6.1.59/60, 6.3.04 Neuropore caudal 6.4.0103 cranial 1.2.02, 1.3.24, 3.1.05, 6.1.02/12, 6.2.01 Nose 2.2.0131 choana, primary 2.2.1721/2427, 2.3.03 concha 2.2.22/23, 2.4.04 external 1.2.17/27/29/36/37, 1.3.34/35, 2.2.09, 2.3.13 lacrimo-nasal groove 1.2.12/15/23/27/28/3436, 2.2.07 nasal cavity 2.2.1023 nasal pit 1.1.10, 1.2.07/08/10/22/33, 1.3.17/19/20/43, 2.2.04/1014 nasal placode 1.1.02/0509, 1.2.05/06/20/31/32, 1.3.04/06/1214/18/31, 2.2.0103, 6.1.32 nasal prominences 1.2.07/0915/21/2325, 1.3.21, 2.2.0408/1113/16/24, 2.3.03 nasal septum 2.2.25/26/2831, 2.3.09, 2.4.04 nostril 1.2.1214/16/17/23/24/26/28/29, 1.3.12/3335/42, 2.2.0609, 2.2.1722, 2.3.03, 2.4.02 vomero-nasal organ 2.2.21 Notochord 1.5.23, 6.4.04/05
Oesophagus 1.4.38, 2.5.01/02/04/09/13, 2.6.04, 4.4.27 Omental bursa 4.4.20/22/2427, 4.5.05, 4.6.0610/1214/16 Omentum greater 4.4.14, 4.5.02/04/06 lesser 4.4.14/20/21, 4.5.06 Oral cavity 2.1.0137
Palate 2.3.0114 hard 2.2.31, 2.3.12/14, 2.4.05 palatal processes 2.1.37, 2.2.24/26/29/30, 2.2.25, 2.3.0312, 2.4.0204, 6.3.23 palatine tonsil 2.4.05/06 palatoglossal arch 2.4.05
513
Palate (continued) palatopharyngeal arch 2.4.05 primary 2.1.37, 2.2.22/26/29/30, 2.3.0406/08/09/12, 2.4.04 soft 2.3.12/14, 2.4.05 Pancreas 4.4.22/23/25/26, 4.5.05, 4.6.0116 position 4.6.0608/13/14 Perineum 1.6.2226, 5.2.1214 Pharyngeal arch(es) arteries, see Artery(ies) cervical sinus 1.1.05/10, 1.2.32, 1.3.0911/1320/39/41/4346 external aspect 1.1.0212, 1.2.0137, 1.3.0153 hypopharyngeal eminence 2.1.02/03/13/19, 2.5.07 internal aspect 2.1.0105, 2.1.1113, 2.1.31, 2.1.1922, 2.1.24/25, 2.4.0712, 2.5.07/08 Pharyngeal pouches 2.1.0104/11/12, 2.6.01/03 Pharynx 2.2.31, 2.4.0111, 2.5.02/04/12/13 copula 2.1.06/08/1921 epiglottis 2.1.04/24/26, 2.4.0911, 2.5.0811 Primitive streak 6.4.01
Somite 6.4.02/04 Spinal cord 1.5.23, 6.4.04/05 neural fold 6.4.01/02 Spleen 4.4.14, 4.5.0110, 4.6.13 form, external 4.5.0610 position 4.5.0205/0710 Stomach 3.2.07/2225/27/29/31/34, 4.1.14/16/17, 4.2.14, 4.3.07/09, 4.4.0127, 4.5.01/0306, 4.6.04/07/12/13 form external 4.4.0914, 5.1.04 endoderm 4.4.15/16 internal 4.4.1719, 4.4.27 position 4.4.0108
Thymus 2.5.12, 2.6.0105 Tongue 2.1.0126, 2.2.20/22/28, 2.5.08, 2.3.13, 2.4.08, 6.3.12/24 copula, see Pharynx foramen caecum 2.1.01/03/12/24/3133, 2.4.07, 2.5.05
514
lingual swellings 2.1.03/04/06/1113/1921/24, 2.4.0810, 2.5.08, 6.3.20 pharyngeal part 2.1.2426/32, 2.4.0811 Tooth 2.1.2730 bud 2.1.2830 bell-shaped 2.1.30 Trachea 1.4.38, 2.5.0104/06/07/13, 2.6.04, 3.2.06/12/51 bifurcation 3.2.08/51
Umbilical cord 1.1.03/05/0709/11/12, 1.3.19/21, 1.5.04/15, 4.3.04/07 Umbilical vesicle 1.1.01/02, 4.1.0104 Ureter, see Metanephros Urethra mllerian tubercle 5.2.14, 5.4.07/08, 5.4.09, 5.6.05/06/10/11 pelvic part 5.2.11/13/14, 5.3.06, 5.4.0709, 5.6.05/11 phallic part 5.2.10/1214, 5.3.15/16, 5.4.01/02 urethral fold 1.6.1322 urethral groove 1.5.22/29, 1.6.0122, 5.4.01 Urinary bladder 1.5.20, 5.2.0510, 5.3.01, 5.4.01/02, 5.4.0409 Urogenital sinus 5.2.0114, 5.3.01 urorectal septum 5.2.0209 Uterine tube 5.5.07, 5.6.03/04 abdominal end 5.6.07/08 mbriae 5.6.08
3.1.01/15/46/55/56, 3.2.13/15/17/19/22/26/28/30/31/34/55/ 57/60, 3.2.19, 4.2.12/24, 4.3.01/02/1517 inferior 3.1.01/46, 3.2.07/13/15/17/19/26/28/30/33/62, 4.2.12, 3.2.19, 4.3.01/02/1417, 4.4.03 superior 2.4.13, 3.1.52/56/88, 3.2.15/17/19/23/26/28/30/31/59/60, 4.2.12/16, 3.2.19, 4.3.01/02/1418, 4.4.04, 6.1.25/58/60, 6.3.05 caval inferior 3.1.53, 4.3.12/13, 4.4.21 superior 1.4.38, 3.1.53/70 hepatic 3.1.15/56, 3.2.13/62, 4.2.15/17/24/26, 4.3.1113, 4.4.09/21, 5.1.02 jugular 6.3.13
515
Vein(s) (continued) liver 4.2.15/1822/24, 4.4.03 mesenteric superior 4.1.05, 4.2.26, 4.3.13, 4.4.21/22/24/26, 4.5.05, 4.6.01/ 05/06/09/10/12, 5.5.03 portal 4.2.15/16/18/19/24/26, 4.3.12, 4.4.20/21 postcardinal 5.3.07/12/16, 5.4.05, 6.4.05 subcardinal-hepatic anastomosis 4.2.17/25/26, 4.3.11/12 umbilical 1.5.23/25, 1.6.09, 4.1.10, 4.2.04/06/08/10/1214/16, 4.3.0105/ 0810/12/13/15, 4.4.05, 4.6.05
516