Embryology of Facial Tissues: DR Sana Javed
Embryology of Facial Tissues: DR Sana Javed
Embryology of Facial Tissues: DR Sana Javed
TISSUES
DR SANA JAVED
LEARNING OBJECTIVES
You should be able to describe
• Development of Face, Tongue, Palate, Maxilla
and Mandible
• Clinical conditions related to development of
facial tissue
DEVELOPMENT OF THE FACE
• It is controlled by the proliferation and migration
of ectomesenchyme involved in the formation of
the primitive nasal cavities
• Face develops between 24 and 28 day of gestation
• At about 28 day, localized thickenings develop
within the ectoderm of the frontal prominence
just rostral to the opening of the stomatodeum,
are called OLFACTORY PLACODES
• Proliferation of the underlying mesenchyme
around the placodes bulges the frontal
prominence forward and produces a horse-
shoe shaped ridge which converts the
olfactory placodes
Frontal
into the nasalpit. prominence
Medial nasal
Nasal pit process
Lateral nasal
process
Maxillary
process
Mandibular
process
THE FACE OF 4 WEEK EMBRYO
A)- Frontonasal
process
B)- Mandibuar
processes
C)- Maxillary
processes
D)- Pericardial
swelling
• The lateral arm of the horse shoe is
called the lateral nasal process and the
medial arm is the medial nasal process.
• The region of the frontal prominence
where the nose will develop is referred
as the frontonasal process.
• The medial nasal processes of both sides
together with the fronto nasal process,
give rise to the middle portion of the
nose, middle portion of the upper lip,
anterior portion of the Maxilla, and the
primary palate
• Two mandibular processes merge to form
lower lip.
• Merging of two medial nasal processes forms
the maxillary portion of incisor teeth, primary
palate and part of the lip.
Medial nasal
process
Lateral nasal
process
Maxillary
process
Mandibular
process
• The maxillary process grows medially and
approaches the lateral and medial nasal
processes but remains separated from them
by distinct grooves, the nasolacrimalgroove.
THE FACE OF 6-WEEK OLD EMBRYO
• Proliferation and thickening of epithelium
at the inferior border of the maxillary
process and the superior border of
mandibular arch forms odontogenic
epithelium.
• Odontogenic epithelium also develop on
the lateral aspect of medial nasal process.
• The primary epithelial band is an arch-
shaped continuous plate of odontogenic
epithelium that forms in the upper jaw
&lower jaw.
Frontal prominence
Maxillary process
Mandibular process
Odontogenic
epithelium
CLINICAL CORRELATION
• Oblique facial cleft = Lack of fusion between
the maxillary process and lateral nasal process
• Median cleft lip = (harelip) Lack of fusion
between the two medial nasal processes
• Bilateral cleft lip = Lack of fusion between the
maxillary process and median nasal process
• Microstomia= Excessive merging of the
mandibular and maxillary processes
• Macrostomia = Failure of the maxillary and
mandibular processes to fuse
Normal Unilateral cleft lip
(Common)
Oblique facial
Median cleft
cleft.
Tuberculum impar
Hypobranchial
eminence
Palatine
Epiglottis tonsil
• As the tongue develops, the hypobranchial
eminence overgrows the copula gives rise to the
mucosa of posterior third covering the root of the
tongue
• Tongue separates from the floor of the mouth by a
downgrowth of ectoderm around its periphery,
which degenerates to form the lingual sulcus and
gives mobility to the tongue.
• Muscles of tongue have different origin, they arise
from the occipital somites which have migrated
toward into the tongue area, carrying with them
their nerve supply (hypoglossal nerve)
• Anterior two third of tongue is supplied by
lingual branch of trigeminal nerve as mucosa
is derived from 1st arch while mucosa of
posterior third is derived from 3rd arch
&supplied by glassopharyngeal nerve
• Adult tongue is formed from 1st,3rd and 4th arch
CLINICAL CORRELATION
• Ankyloglossia (Tongue-tie)= Occurs when
frenulum of tongue extends to the tip of the
tongue, thus preventing protrusion.
• Aglossia = Complete absence of tongue.
• Microglossia = Small sized tongue.
• Macroglossia = Large sized tongue.
• Bifid tongue = Failure of fusion between 2
lingual swellings.
DEVELOPMENT OF PALATE
Septum
Septum
Palatal shelf
Palatal shelf
Tongue Tongue
7 weeks 8 weeks
A) Palatine
shelves
B) Secondary
nasal septum
C) Midline
epithelium
D) Developing
bone of maxilla
• Nasal septum and shelves converge and fuse
along the midline, separating the primitive
oral cavity into oral and nasal cavities.
Septum
Palatal shelf
Tongue
9 WEEKS
• Closure of secondary palate proceeds
gradually from the primary palate in a
posterior direction.
• By displacement of the tongue between the
palatine shelves due to growth of the head.
• The primary & secondary palate fuse at the
incisive foramen to form the definitive adult
palate
• For fusion of the palatine shelves and fusion of
any other processes, elimination of the
epithelial covering of the shelves is necessary.
• The head is folded onto the developing
thoracic region and the tongue occupies an
elevated position between the palatine
shelves
Cleft of lip and primary palate Unilateral cleft lip and palate
Bilateral cleft lip and primary palate Bilateral cleft lip and palate
Mandibular nerve
Lingual branch
Mental branch
Incisive branch
• During the 6th week of development, on the lateral
aspect of the cartilage, condensation of
mesenchyme occurs in the angle formed by the
division of the inferior alveolar branches and its
incisor and mental branches.
• At 7th week, intramembranous ossification begins in
this condensation, at a site close to the future
mental foramen forming the first bone of mandible
• Bone formation spread from this centre of
ossification, anteriorly to the midline and
posteriorly towards the point of bifurcation of
lingual and inferior alveolar nerve.
• The two separate centers of ossification
remain separated at the symphasis until birth.
• A backward extension of ossification along the
lateral aspect of the Meckel's cartilage corresponds
to future a body of mandible
• Ramus of mandible develops by a rapid spread of
ossification posteriorly into the mesenchyme of the
1st arch, turning away from Meckel's cartilage.
Meckel’s Spine of
cartilage sphenoid
Perichondrium
becomes
sphenomandibular
ligament
Lingula
• By the10th weeks, the rudimentary mandible is
formed entirely by membranous ossification.
• Further mandibular growth until birth is strongly
influenced by the appearance of three secondarily
growth cartilages (condylar, coronoid and
symphyseal cartilages).
• Condylar cartilage appears during the 12th week
and rapidly forms a cone shaped mass occupying
most of the ramus and converting to bone by
endochondral ossification.Remains functioning upto
16th year of life
Tongue
Dental
lamina
Meckel’s
cartilage
Developing
mandible
• Coronoid cartilage appears about 4th month of
development, surround the anterior border and top
of the coronoid process,Disappears long before
birth.
• Symphyseal cartilages appears in connective tissue
between the ends of Meckel's cartilage,Disappears
with in the first year after birth.
• Mandible is a membrane bone, developed in
relation to the nerve of the first arch and almost
entirely independent of Meckel’s cartilage.
• The mandible has neural, alveolar, and muscular
elements and its growth is assisted by the
development of secondary cartilages.
DEVELOPMENT OF MAXILLA
Nerve
Developing
Bone
Tooth germ
• The deposition of bone results in the
formation of a bony trough for infra orbital
nerve.
• From this trough, a downward extension of
bone forms the lateral alveolar plate for the
tooth germs.
• Ossification spreads into the palatine process
to form hard palate
• Medial alveolar plate develops from the
junction of palatal process and main body of
the forming maxilla.
• Zygomatic or malar cartilage contributes to
the development of maxilla
At birth:
• Frontal process of maxilla is well marked, but the
body of the bone consists of little more than the
alveolar process containing the tooth germs and
small though distinguishable zygomatic and palatal
processes.
• The body of maxilla is small as maxillary sinus has
not developed.
• Sinus is about the size of small pea.
• Sinus forms during the 16th week as a shallow
groove on the nasal aspect of developing maxilla.
SIMILARTIES B/W DEVELOPMENT OF
MAXILLA & MANDIBLE
• Single center of membranous ossification
related to a nerve
• Form a neural element related to the nerve
• Develop an alveolar element related to the
developing teeth.
DISIMILARTIES B/W DEVELOPMENT OF
MAXILLA & MANDIBLE
• No primary cartilage in maxilla
• No secondary cartilages develops in maxilla