Neurulation

Question 1

What happens during week 3 of development and why?

Answer 1

Broadening of cranial end allowing specification of cells in ectoderm to become neural cells (neuroectoderm)

Question 2

what induces the production of epidermis from ectoderm?

Answer 2

BMPs (BMP-4)

Question 3

How is neuroectoderm formed?

Answer 3

Increased expression of chordin, noggin and follistatin leads to inhibition of BMP signalling

Question 4

How are the neural folds and neural groove formed?

Answer 4

End of 3rd week, lateral edges of neural plate becomes elevated to form neural folds, and the depressed midregion forms neural groove

Question 5

How is the neural tube formed?

Answer 5

Neural folds approach each other and fuse on midline. Fusion begins in cranial region and proceeds craniocaudally creating neural tube.

Question 6

when do the anterior and posterior neuropore close?

Answer 6

Anterior: day 25
Posterior: day 27

Question 7

Name open NTDs

Answer 7

Cranioschisis (brain)

Myeloschisis (spinal cord) i.e. spina bifida aperta

Question 8

Name skin covered NTDs

Answer 8

Encephaloceles

Question 9

What are the causes of NTDs?

Answer 9

1. Varies by race
2. Mutuations
3. Linked to teratogens
4. High insulin
5. Valproic acid