2. During face development
There is a common oro-nasal cavity occupied
by developing tongue
Separation between oral and nasal cavities
occurs by developing of the palate
6. primary palateprimary palate
• Called primary as it
forms initial separation
between oral and nasal
cavity
• It is formed of the
posterior part of the
intermaxillary segment
between incisors
and incisive fossa
Primary
palate
7. Derivtives of the intermaxillary segment:
2- The anterior portion of the maxilla carrying the incisor teeth
(pre-maxilla).
1- Middle portion of the upper lip
(philtrum)
3-The anterior portion
of the palate called
(primary palate).
9. Medial nasal process
The nasal pit deepens to form a nasal sac which is
separated from the stomodeum by the naso-buccal
membrane double layer ectodermal membrane.
Lateral nasal process
Nasal pit
At 6 WIU
10. * The naso-buccal membrane breaks down to form
the nasal duct which communicates the primitive
nasal & oral cavities. (nasal sac and stomodeum)
11. * The ectoderm of the roof of the primitive nasal
cavity differentiate into olfactory epithelium
14. 1- The oral cavity increase in height and the nasal
septum grows backward.
2- Oral cavity communicates with nasal cavity.
3- The tongue is narrow and high and it reaches the nasal
septum .
At 6 W.I.UAt 6 W.I.U
4- The roof of the oral cavity is
horse shoe shape formed of:
•Primary palate anteriorly
• Horizontal surface of maxillary
process laterally
15. 5- Each maxillary process sends 2 downwards, vertical
palatine processe on the sides of the tongue.
Tongue
Max.
Process
Nasal
Septum
Palatine
process Mandibular
arch
Fore
Brain
20. 1- Contractile fibroblasts in the palatine processes.
2- Differential growth (oral side of the process grows
faster than nasal side).
3- Mesodermal proliferation at the angle between
palatine process and maxillary process from oral side.
The 2 vertical palatine process become horizontal in position
due to :
4- Growth of the mandible and downward movement of
the tongue.
22. 8- The 2 palatine shelves will unite together and
with the primary palate and with nasal septum in Y
shape.
9-The direction of union start at center of the Y and
extend anteriorly and posteriorly.
26. Sec. palate gives rise to:
most of the hard palate
soft palate&
uvula
27. For fusion of palatine shelves to occur and for fusion
of any other processes, it is necessary to eliminate
their epithelial covering at the line of fusion
Mechanism of fusion of the 2 palatine process :
Then mesoderm will invade the line of fusion.
28. 1- Cessation of DNA synthesis in the epithelial cells at
line of fusion 24- 36 hours before contact
3- The basal epithelial cells have carbohydrate rich cell
coat.
5- Mesodermal proliferation invade the midline seam
which thin and breakdown into discrete islands
6- The islands lose their basal lamina and undergo
mesenchymal transformation or phagocytosed
Mechanism of fusion of the 2 palatine process :
2- sloughing of surface epithelial cells by apoptosis
(Apoptosis is physiological cell death)
4- fusion of the basal epithelial cells of the 2 processes to
form midline seam.
29. Cleft palate:
• Malunion between two 1ry palate, palatineMalunion between two 1ry palate, palatine
processes andprocesses and nasal septum.
• It may beIt may be unilateral or bilateral.unilateral or bilateral.
• May beMay be anterior or posterioranterior or posterior