9. Zippering action -Closure of Neural
Tube
Completes in
25days post
embryonic
development
Completes in 27
days post
embryonic
development
Apical constriction by
rearrangement of
actin, tubulin effect of
BMP4/7 signaling
Basal bulging out caused by
movement of nucleus into this
space signaled by shh from
notochord
13. DEFECTS……..
ANENCEPHALY SPINA BIFIDA
END OF NEURROSTRAL
AL TUBE FAILS TO
CLOSE
MISEPRESSION OF WRONG CADHERIN
LEADS TO FAIL TO SEPARATE
EPIDERMAL ECTODERM AND NEURAL
LAYER
15. Unfortunately, simplicity is not the answer.
In actuality, the folding of the neural tube is still not entirely
understood.
The simplistic model of the closure occurring in one step
cranially and caudally does not explain the high frequency of
neural tube defects.
Proposed theories include that closure of the neural tube occurs
in regions, rather than entirely linearly