neurulation Flashcards
what do neural crest cells form?
pns ganglia
glia
cartilage of jaw
human neurulation occurs at what dates?
embryonic day 17-28 (out of 280 days)
initiation of neurulation is where?
closure sites 1, 2, 3`
neurulation completed with closure at what sites?
neuropore
ntd
neural tube remains open at some point along rostro-caudal (anterior posterior) axis
NTD - exencephaly
- Failure of neural tube closure in brain
- Exposed neural folds degenerate, leading
to anencephaly - Lethal at or before birth
NTD - craniorachischisis
Failure of closure in midbrain, hindbrain
and spine
* Usually lethal at birth
NTD - spina bifida
Failure of neural tube closure in lower
spinal level; meninges and spinal cord
protrude outside of the vertebral column
* Fetus often survives
* in utero surgery can improve functional
deficits
lamellipodia (protrusion of cells)
lamellipodial protrusions are polarised (mediolateral extension)
attach to and pull on neighbouring cells -> elongating and pull between one another
PCP pathway
neural tube defects
neural plate and the
underlying notochord fail to elongate along the A-P axis, due to
failure in directed migration and, consequently, ineffective cell
intercalation at the midline.
= neural plate too wide cant apposit / contact sides
hinge point(s) in upper spine
mhp only
dlhp blocked by bmp2
hinge point(s) in cranial and lower spine
dhlp and mhp
bmp2 inhib by noggin
neural tube adhesion molecule
n-cadherin
ectoderm adhesion molecule
when ectoderm forms over neural tube
e-cadherin
folic acid and NTD prevention
req. for production of purines / pyrimidines for DNA syn
overcome effects of adverse conditions maybe
important for apical constriction (neural plate bending)
