Bilaminar/Trilaminar Stage

Question 1

When does Neurulation start to form?

Answer 1

Week 3-5: 

Ectodermal induction—forming the neural plate.

Neural plate subsequently curls, forming the neural tube.
Neural tube begins to close centrally and continues to each end

Question 2

What is it guided by?

Derived from?

Parrallels the -

Elongates which way?

Answer 2

Guided by the notochord
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Derived from the primitive knob
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Parallels the mesodermal plate

Elongates cranially first, then adds caudally

Question 3

Failure of closure can cause?

Answer 3

•
Cranially—anencephaly
•
Caudally—spina bifida

Question 4

What are neural crest cells?

Answer 4

Neural Crest Cells—a population of ectodermal cells.
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Run parallel to the closed neural tube
•
Forms the peripheral nervous system

Question 5

What happens in week 6-8?

Answer 5

Segmentation.

Each vertebra forms from each adjacent sclerotomes.

Notochord begins to degenerate between the vertebrae.
•
Persists to form the nucleus pulposus

Chondrification begins here.