Lecture 8: Neurulation and Neural Crest

Question 1

What is the importance of the notochord? (2)

Answer 1

• template for vertebral column (contributes to IV discs)

- induces neural plate (from ectoderm) –> forms CNS

Question 2

What does the neural crest form?

Answer 2

spinal ganglion

Question 3

What does the neural tube give rise to?

Answer 3

CNS (spinal cord and brain)

Question 4

Primary Neurulation vs Secondary Neurulation

Answer 4

Primary –> brain to lumbar spinal cord

Secondary –> saccral and coccyx

Question 5

When do the rostral and caudal neuropores close?

Answer 5

Rostral –> Day 25

Caudal –> Day 28

Question 6

Neural Crest Derivatives

Answer 6

• spinal and autonomic ganglia
• Schwann cells (myelinate PNS)
• pigment cells (melanocytes)
• connective tissue

Question 7

Failure of Caudal Neuropore to close:

1. Spina bifida occulta
2. Meningocele
3. Meningomyelocele
4. Myelocele (myeloschisis)

Answer 7

1. failure of caudal neuropore to close (hair tuft) –> prevent with B9 (Folic Acid)
2. vertebral lamina not present (subarachnoid space herniates out)
3. spinal cord and subarachnoid space herniates out
4. open spinal cord

Question 8

Failure of Rostral Neuropore to close:

1. Anencephaly
2. Encephalocele

Answer 8

1. missing top of skull (exposed brain)

2. cysts with or without brain tissue (use imaging to detect)

Question 9

Meninges:

1. Meninx Primitiva
2. Pachymeninx
3. Leptomeninges

Answer 9

1. mesoderm in origin (from sclerotome cells)
2. forms dura mater from mesoderm AND neural crest cell
3. forms arachnoid and pia mater from neural crest

Question 10

When does folding of the embryo occur?

Answer 10

4th week