1. DEVELOPMENT OF FACE AND
ORAL CAVITY

2. Origin Of facial Tissues
fertilization ovum egg cell mass (morula)
epiblast, hypoblast inner cell mass
the anterior end of the primitive streak form
endoderm which embedded the midline
notochondral, prospective mesodermal cell
migrate from the epiblast through the
primitive streak to form mesoderm, cell
remaining in the epiblast form ectoderm,
completing formation of the three germ layer

3. HUMAN EMBRYOGENESIS

7. • Figure 2-11 A, The mesoderm, situated between
the ectoderm and endoderm in the trilaminar
disk. B, Differentiation of the mesoderm into
three masses: the paraxial, intermediate, and
lateral plate mesoderm. C through E, With lateral
folding of the embryo, the amniotic cavity
encompasses the embryo, and the ectoderm
constituting its floor forms the surface
epithelium. Paraxial mesoderm remains adjacent
to the neural tube. Intermediate mesoderm is
relocated and forms urogenital tissue. Lateral
plate mesoderm cavitates, the cavity forming the
coelom and its lining the serous membranes of
the gut and abdominal cavity.

8. Development of Facial Prominences
• Development of nasal placodes, frontonasal
region, primary palate, and nose
• Development of maxillary prominences and
secondary palate
• Development of visceral arches and tongue

9. Development of nasal placodes, frontonasal
region, primary palate, and nose
• Thickening of the surface ectoderm on either
side of the frontal prominence just above the
stomodeum is the first indication of the nasal
cavity called the nasal (olfactory) placodes
• Nasal placodes are ectoderm induced by
ventral forebrain
• At this time there are 5 prominence and 2
nasal placodes

12. • Nasal (olfactory) pits are located on either side of
the frontonasal prominence and are surrounded
by horseshoe-shaped eminences. The medial
portion of these eminences is called the medial
nasal process (MNP). The lateral portion of which
is called the lateral nasal process (LNP). The
lateral nasal process is separated from the
maxillary process (the more rostral portion of the
first branchial arch) by a furrow which reaches
the medial aspect of the developing eye.

14. • Figure 3-17 Human facial development from 24
days through 38 days. Left-column photographs
shows actual embryos; the middle and right
columns are diagrams of frontal and lateral
views. A, Boundaries of the stomatodeum in a
26-day embryo. B, A 27-day embryo. The nasal
placode is about to develop, and the odontogenic
epithelium (white bars) can be identified. C, A 34-
day embryo. The nasal pit, surrounded by lateral
and medial nasal processes, is easily
recognizable. D, A 36-day embryo shows the
fusion of various facial processes that are
completed by 38 days (E)

15. • The anterior aspect of this partition is derived
from the area of the upper jaw formed by the
medial nasal processes (intermaxillary
segment) and is called the primary palate
(median palatine process).

17. Development of maxillary prominences
and secondary palate
• Most of the palatine partition, is derived from
the medial growth of shelf-like processes
originating from the maxillary process called
the palatine shelves (lateral palatine
processes). This segment of the palate is
called the secondary palate. As the secondary
palate is formed, the nasal septum grows
inferiorly toward it. The nasal septum and the
two palatine shelves unite to form separate
right and left nasal chambers

18. • Most of the hard palate and all of the soft
palate form from the secondary palate

19. Development of visceral arches
and tongue
• In humans there are six visceral arches, which
the fifth is rudimentary.
• The proximal portion of the first arch becomes
maxillary prominence, the mandibular and
hyoid arches develop at their distal portion to
become consolidated in the ventral midline
• Nerve fibers from 5, 7, 9, and 10 cranial
nerves extend to the mesoderm of the first
four visceral arches.

22. • Figure 3-22 Development of the tongue. A, The floor of
the primitive stomatodeum, viewed from above, is
formed by the branchial arches. Three swellings, the
tuberculum impar and the paired lingual swellings,
appear in the mesenchyme of the first arch beneath
the epithelium. A midline swelling (the hypobranchial
eminence) appears in the third arch; the sagittal
section through the arches is shown in the lower
drawing. B, The increased swelling of the lingual
swellings, together with the tuberculum impar, will
form the anterior two thirds of the tongue. The
hypobranchial eminence overgrows the second arch
(depicted in the sagittal section in the lower drawing).
C, Final disposition of the tongue and the relative
contributions of the first and third arches. The sagittal
section is shown in the lower drawing. The arrow
depicts the route of incoming occipital myotomes that
form the tongue muscle.

23. • Know that the anterior two thirds of the
tongue is covered by ectoderm and derived
from first arch mesenchyme
• And posterior one third of tongue is covered
by endoderm and be primarily derived from
the third arch mesenchyme