Transcript m5zn_a2ee964dc9b908b

FACE
DEVELOPMENT
Frontonasal
prominence
Mandibular
prominence
Maxillary
prominence
stomodeum
Maxillary and lateral nasal
prominences are separated
by Nasolacrimal groove
Nasal placode
Frontonasal process
• Latral nasal process
• Nasal pit
• Medial nasal
process (globular
process).
Latral nasal
process
Nasal pit
Medial nasal
process
• Medial N. P.
• Lateral N.P.
• Maxillary P.
• Mandibular P.
Medial
N. P.
Lateral
N.P.
Max. P.
Mand.
P.
PALATE
DEVELOPMENT
The primary palate
• Primary
palate
The secondary palate
• palatal shelf
tongue
tongue
The motive force for shelf elevation is not
clearly elucidated:
• Contractile fibroblast in the palatine processes may
be involved.
• The displacement of the tongue downward helps in
the elevation of the two palatine processes.
• The oral surface of the folds grows more rapidly than
nasal surface that occurred by differential growth of
the mesoderm, thus leading to rapid change in the
position of the fold away from the faster growing
side.
tongue
• Medial n.p.
• Lateral n p
• Maxillary p
• Palatin p.
• Medial n.p.
• Lateral n p
• Maxillary p
• Primary
palate
• Palatin p.
Fusion of palatine processes
For fusion of palatal shelves to occur and for
fusion of any other processes, it is necessary to
eliminate their epithelial covering at the line of
fusion
• To achieve this fusion there is cessation of DNA synthesis and cell
division within the epithelium 24-36 hours before epithelial contact.
• This leads to sloughing of the surface epithelial cells and then they
undergo physiologic cell death (apoptotic cell death) to expose
basal epithelial cells.
• These basal cells have an extra cellular surface substances
particularly glycopoteins that enhance adhesion between the shelf
edges as well as between the shelves and inferior margin of the
nasal septum.
•
The epithelial cell debris is phagocytosed by ectomesenchymal
cells. Not all the epithelial cells are lost in this process some cell
rests remain in clusters (cell rests) along the fusion line.
•
Recent studies indicate that some epithelial cells undergo direct
transformation to mesenchmal cells.
TONGUE
DEVELOPMENT
Tongue is composed of:
• Mucous membrane
• Muscles( intrinsic and extrinsic)
• Papillae( filiform, fungiform, circumvallate,
foliate)
• Salivary gland
• Lingual tonsil
Tongue Mucous
Membrane
1st arch
2nd arch 3rd arch
• Anterior two
thirds
• Posterior
third
• Epiglottis
Summary
Development of the tongue
muscles
• During the 2nd month IU the muscles of the
tongue develop (intrinsic and extrinsic).
• Some authors believe that the intrinsic muscles
of the tongue are derived from the mesenchyme
of the branchial arches sharing in the tongue
development.
• The intrinsic and extrinsic muscles of the tongue
are developed from the occipital myotomes.
These myotomes migrate and invade the tongue
to from its musculature and carrying with them
the hypoglossal nerve.
Tongue papillae
1- Filliform pap.
2- Fungiform pap.
Taste bud
4- Folliate pap.
3- Circumvallate pap.
Development of circumvallate papilla
Taste bud
Taste pore
1- Outer supporting cell
2- Inner supporting cell
3- Neuroepithelial cell
Taste sensation
Bitter
Sour
Salt
Sweet
Innervation of the tongue:
• A-Sensory innervations:
• 1-Anterior two thirds (Lingual
nerve and Chorda tempani)
• 2-Posterior one third
(Glossopharyngeal nerve)
• B-Motor innervation:
Hypoglossal nerve.