DR - Suryadi Embriologi Prenatal PDF
DR - Suryadi Embriologi Prenatal PDF
DR - Suryadi Embriologi Prenatal PDF
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Early division of zygote into multiple cells
Cleavage without increase in size, partitions
contents
Morula
solid ball of cells
Zygote
Blastocyst
with blastocoele cavity
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UMUR 3 SAMPAI 7 MINGGU
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Introduction
Embryology is the study of the development of Embryo or
a part of Developmental Anatomy
Developmental anatomy is continuous process
That begins when an ovum is fertilized by a sperm
until ends at death
A process of change and growth which transform the
zygote as a single cell into a multi cellular, multi
tissues, multi organs in adult human body
Development usually divide into prenatal and post natal
Natal (=birth) is a dramatic event during development
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Term of Prenatal Period
Zygote: the cell result from fertilization of an ovum
by a sperm
Cleavage: Mitotic division of zygote
Formation of daughter cells (=blastomeres) become
smaller and smaller
Blastomere is totipotent cell or multi-potent cell
Morula: when 16 blastomeres have formed
Blastocyst (=blastula) = forming a cavity this
converts from the morula into a blastocyst
Embryo: developmental stage from the bilaminar
embryonic disc form until all major structure are
present (2nd – 8th week)
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Fetus:
Prenatal period after the embryonic period
(8th) to birth
Concepts:
The product of conception it includes all
structure which develop from zygote to
both embryonic and extra embryonic
tissues
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Stages of development
• Early development is blastulation (the first week)
• Formation of the bilaminar embryo and implantation
(the second week)
• Formation of the trilaminar embryo and
morphogenetion (the third week)
• The embryonic period and organogenetion( the
fourth to the eight week)
• The fetal period (the ninth week to birth)
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The First Week
Fertilization
Consist of the fusion of sperm and a ovum
This process occur as follows
1. The sperm passes through the corona radiata
2. The sperm penetrates the zona pellucida
3. The sperm head attaches to the surface of the
ovum
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4. The ovum reacts to sperm contact two ways
a. Changes occur in the zona pelluzida and ovum’s
cell membrane which prevent polysperm
b. The oocyt continue second meiotic division
process and expels the second polar body and the
female pronucleus formation
5. Sperm loses its tail and its head enlarge to form the
male pronuclei
6. The male and female pronuclei approach each
other in the center of the ovum
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Result of Fertilization
1. Restoration of diploid chromosome
number
2. Species variation
3. Sex determination
4. Initiation of cleavage
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Perkembangan minggu pertama
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The first
week
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Hari ke 14
Cleavage
As the zigote passes down the uterine tube
undergoes cleavage into a number of small
blastomeres
About three days after fertilization a ball
form contain 16 blastomeres called the
morula, enters the uterus
Blastomere is totipotent cells
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Blastula
A cavity soon forms in morules, called blastocyst
consisting of
an inner cell mass (or embryoblast), which gives
rises to the embryo
A blastocyst cavity, which become primitive yolk sac
An outer layer at cell (or trophoblast), which
enclose the inner cell mass and blastocyst cavity
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On fourth and fifth day the zona pellucida
degradations and disappears and on sixth day
the blastula adheres to the endometrial
epithelium
The trophoblastic cells invade the epithelium
and stromes endometrium
The trophoblast gradually differs into two layer
1) An inner cytotrophoblast
2) An outer syncytrotrophablast
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On seventh day the embryonic endoderm
begins to form on the ventral surface at
the inner cell mass. This is the first primary
germ layer
The blastocyst beginning implanted in the
endometrial living of the uterus
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The second week: implantation and chorion formation
Implantation:
begins at the end at the first week and ends during
the second week
Implantation process as follow
1. Zona pellucida disappears (4-5)
2. Blastocyst attaches to endometrial epithelium (6)
3. Trophoblast erodes epithelium and endometrial
stroma (7)
4. Trophoblast will be differed into cytotrophoblastic
and syncytiotrophoblastic layer (7 to 8)
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5. Lacunae appear in syncytrotrophoblast (8 to 9)
6. Blastocyst sinks beneath surface of endometrial
epithelium (9-10)
7. Lacunar networks form (10 – 11)
8. Trophoblast invades endometrium sinusoid, and
establish a uteroplacental circulation (11 to 12)
9. Endometrial epithelium completely re-forms
over the implanted blastocyst (12 to 13)
10. Marked decidual reaction occurs in the
endometrium (13-14)
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Implantation - embedding of blastocyst into
uterine lining begins at day 7
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Chorion Formation
Between squamous epithelium in
blastocyst cavity and cytotrophoblast
arise mesenchym cell called
extraembryonic mesoderm
In the extraembryonic mesoderm form
spaces called extraembryonic coelom
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This coelom splits the extra embryonic
mesoderm into two layers
Extraembryonic somatic mesoderm
Extraembryonic splanchnic mesoderm
The cavity of the chorion sac is formed by the
extraembryonic coelom
The trophoblast and the extra embryonic
somatic mesoderm together form chorione
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The third week
Major changes occur as the bilaminar embryonic
disc is converted into a trilaminar embryo
composed of three primary germ layer
In the third week usually the first sign that a
woman may be pregnant
Laboratory pregnant test depend on the presence
of human chorionic gonadotropin (HCG), a
hormone produced by trophoblast and excreted in
the mother’s urine
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The third week cont……
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The primitive streak (stria primitiva) and
intraembryonic mesoderm
The primitive streak appears at about 15
days as a midline thickening of the
embryonic ectoderm
At the primitive streak give rise to
mesenchymal cells which migrate laterally
and cranially between the ectoderm and
endoderm layers and organize into the third
primary germ layer called intra embryonic
mesoderm
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Mesoderm exists between the ectoderm and the
endoderm everywhere except at the
oropharyngeal membrane and at the cloacal
membrane
At the primitive knot give rise to the notochordal
process to form the notochord
The primitive pit extents into the notochordal
process to form the notochordal canal
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Notochord Formation
Opening develops in the floor at the
notochord canal which soon coalesce, leaving
the notochord plate.
The notochord plate in folds to form the
notochord
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Neural Tube Formation
The neural plate appears as a midline thickening at
the embryonic ectoderm, cranial to the primitive
knot and dorsal to the notochord process
A longitudinal neural grove develops which is
flanked by neural folds, these folds meet and fusion
to form the neural tube
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Somite Formation
The mesoderm on each side at the notochord
thickens to form longitudinal bundle (colum)
of paraxial mesoderm
Division of paraxial mesoderm into pairs at
somites begin cranially by the end at the
third week
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Coelom Formation
The entry embryonic coelom arises as isolated
spaces in the lateral plate mesoderm and
cardiogenic area
The coelomic space subsequently coalesce to form a
single horseshoe-shaped cavity, which eventually
give rise to the body cavities
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Blood And Blood Vessel
Angiogenesis = blood vessel formation
Haemopoesis = blood cell formation
1. Mesenchymal cells aggregate to form isolated
masses and cords known as blood islands called
angioblast
2. Spaces appear within these islands
3. Angioblast arrange themselves around the cavity
to form the primitive endotheliumFormation
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4. Isolated vessels fuse to form networks at
endothelial channel
5. Vessels extend into adjacent areas by endothelial
budding
6. Mesenchymal cells surrounding the primitive
endothelial vessel differentiate into muscular and
connective tissue
7. The primitive heart is formed in the cardiogenic
area
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8. Primitive plasma and blood cell develop from the
endothelial cell as the vessels develop on the
yolk sac and allantois. In embryo first blood
formation occurs in the liver, late in the spleen,
bones marrow and lymph nodes
9. The cardiovascular system is the first organ
system to a functional state (the end of the third
week)
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Villi Formation
The primary villi form on the outer surface at the
chorionic sac from cytotrophoblast cell proliferate
By day 15 the primary villi have begun to branch
and develop central cone at mesenchyme: its are
called secondary villi
Capillaries develop in the villi transforming them
into tertiary villi
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Intervillous Space
Lacunas enlarge and lying between tertiery
villis, called intervillous space (spatium
intervillosum)
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The Fourth To Seventh Weeks
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Folding At The Embryo
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The head fold result in the heart coming to lie
ventrally and brain becoming the most cranial
part at the embryo
The tail fold causes the connecting stalk and
allantois to move to the ventral surface of the
embryo
The external appearance of the embryo is
greatly affected by the formation at the brain,
heart, liver, somites, limbs, ears, nose and eyes
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First & second weeks
development
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Reasonable estimates of the age of
embryo can be determine from
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AGE CR FOOT FETAL
(WEE LENGTH LENGT WEIGH
KS) (MM)* H (MM)* T (G)â€
9 50 7 8
10 61 9 14
Fetus 12
14
87
120
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20
45
110
development: 16 140 27 200
30 280 63 1700
32 300 68 2100
36 340 79 2900
38 360 83 3400
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MAIN EXTERNAL CHARACTERISTICS and AGE
(weeks)
Eyelids closing or closed (9)
Early fingernail development. (10)
Sex distinguishable externally. (12)
Head erect (14)
External ears stand out from head (16)
Vernix caseosa covers skin (18)
Head and body hair (lanugo) visible (20)
Skin wrinkled, translucent, and pink to red (22).
Fingernails present. Lean body (24)
Eyelids partially open (26)
Eyes wide open. Good head of hair often present (28)
Toenails present
(30).
Fingernails reach fingertips (32)
Body usually plump 59
Skema perkembangan konseptus
dalam uterus
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Periode Kritis Perkembangan Embryo
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Literature
• Moore K.L.,Persaud T.V.N. The Developing
Human edisi ke-7. Saunder. USA 2003. 16-42
• Carlson B.M.Patten’s Foundations of
Embryology edisi ke-6.McGraw-Hill.New
York.1996.121-143
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