palate formation part 1 and 2 Flashcards
what weeks is the palate formed?
6-12
what is the function of the primary palate?
DEMARCATES nasal and oral cavities NOT separate
what it the primary palate derived from?
medial nasal prominences and inter maxillary segment
what does the secondary palate separate?
nasal and oral cavity
what are the functions of the secondary palate?
-formation of food bolus
-taste and texture
-speech
what happens on week 6 of secondary palate formation?
mesenchymal cells migrate to form nasal septum
mesenchymal cells migrate to form lateral shelves of palate
-tongue forms upwards
what happens in week 7 of secondary palate formation?
tongue takes up a lot of room- and lateral shelves of palate are forced to move down side of tongue- BUT do not attach to tongue (diff glycoproteins on epithelium)
what happens in week 8 of secondary palate formation?
tongue moves downwards and shelves elevate rapidly and slowly move towards each other to the midline
when does elevation happen in males to females?
males- week 7
females- week 8
what extrinsic factor may force the tongue downwards?
-head lifts from cardiac plate
-nasal height increases
-meckels cartilage formation moves tongue
what are 3 reasons which may cause intrinsic elevation of palatal shelves?
1- hyaluran (GAG) can bind 10 x its weight in water- turgid and drives elevation
2- shortened mesenchymal have contractile features which may help elevate shelves
3-blood flow
as the shelves grow towards each other- what is the midline known as?
epithelial midline
in what way does the palate begin to “zip”?
from anterior to posterior
how long does it take for the palate to fuse ?
4 weeks
is secondary palate formation true fusion of fake fusion?
true fusion
what must happen to the midline epithelium once fused?
it must disintegrate
what would happen If the midline epithelium did not disintegrate?
weak palate- would eventually split
what are the 3 theories of midline epithelial disintegration?
1- epithelium mesenchymal transition where epithelial become mesenchyme cells that go on to form facial structures
2-apoptosis- programmed cell death
3- migration to nasal and oral edges to be part of oral epithelium
what causes fusion problems?
due to epithelial midline remnants
what is the most common congenital disease?
cleft palate/cleft lip
what causes cleft palate/cleft lip in percentages?
20%- mutagenic change
20%unknown
what are the risk factors of CL/CP?
smoking
drugs
alcohol
rubella (virus)
increase in vit a
decrease in folate
explain the TGF3-beta knockout mice research
tgf3-beta was knocked out of mice - clefts formed
- HA has 3 enzymes
-ha 1 and 2 have high molecular weight
-ha 3 has low mw
-only ha 3 was stained in knockout mice
-meaning ha 1 and 2 were absent- so not enough molecular weight to elevate shelves
