Lecture 10

Question 1

What structures are made out of the surface ectoderm?

Answer 1

Anterior pituitary, lens, and cornea

Question 2

What structures are made out of the neural tube?

Answer 2

posterior pituitary, retina, optic nerve, brain, spinal cord

Question 3

What structures are made out of the neural crest cells?

Answer 3

adrenal medulla, autonomic and sensory nerves

Question 4

What happens during the 3rd week of development?

Answer 4

Notochord induces the cells of the overlying ectoderm to differentiate into neuroectoderm

Neuroectoderm contains neural plate and neural groove

Neural tube makes up the CNS
The neural crest cells make up the PNS and ANS

Question 5

When does neurulation occur?

Answer 5

On the 22nd day at the occipital and cervical region

Question 6

What are the two initial zones of spinal cord development?

Answer 6

The marginal zone and the ventricular zone

Question 7

What does the ventricular zone give rise too?

Answer 7

ventricular zone = give rise to neurons and microglia in the spinal cord

Question 8

What do the cells in the ventricular zone called when they multiply and form new cells?

Answer 8

The intermediate layer

these cells will eventually form neurons

Question 9

What does the intermediate zone form?

Answer 9

pair of alar plates (dorsal horns and dorsal gray columns)

pair of basal plates (ventral somatic motor and lateral horns)

Question 10

What separates the alar and basal bodies?

Answer 10

sulcus limitans

Question 11

gray matter vs white matter?

Answer 11

intermediate zone forms gray matter

marginal layer forms the white matter

Question 12

Where do microglial cells derived from?

Answer 12

mesenchyme

Question 13

What are neurons and most support cells derived from?

Answer 13

neuroepithelium

Question 14

When does myelination start?

Answer 14

late during fetal development through the first year of life

Question 15

How are the vertebra develop?

Answer 15

mesenchyme of the pair of sclerotomes which surround the neural tube and the notochord at each level

Question 16

What are the two regions of the sclerotome?

Answer 16

Caudally placed, densely packed cells→ forms intervertebral disc and part of vertebral body

Cranially placed, loosely packed cells→ forms vertebral body together with rest of dense tissue

Question 17

What region of the sclerotome is the spine formed from

Answer 17

Intervertebral disc develops from the caudal dense part of the Sclerotome

It forms the anulus fibrosus of the disc

Question 18

What are the ossification centers on the vertebra and when do they develop?

Answer 18

1. the body (5th and 6th weeks)

2. two neural arch centers (7th week)

Question 19

Explain chordoma?

Answer 19

The notochord in the region between developing vertebral bodies persists and forms the nucleus pulposus

It is a slow growing, rare malignant tumor when remnants of the notocord remain

may spread to the bones, but most frequently at the base of the skull.

Question 20

spina bifida occulta?

Answer 20

1. no bulge over the bony defect
2. no neurological impacts
3. a tuft of hair or dimples may be present

lumbosacral region

Question 21

spina bifida (cystica with meningocele)?

Answer 21

1. Bulge is seen over the defect
2. Contains meninges & CSF in the subarachnoid space

neurological defects are uncommon
lumbar presentation is most common

Question 22

spina bifida (cystica with meningomyelocele)

Answer 22

1. Bulge is seen over the defect
2. Contains meninges, cord & nerves

Severe neurological deficits are common ranging from paralysis, sensory loss, bladder dysfunction.

Question 23

spina bifida (cystica with myeloschisis)

Answer 23

Skin and bony defect with “open” spinal cord, seen as a mass of neural tissue

Question 24

meroencephaly?

Answer 24

failure of rostral neuropore to close

absence of a large part of the brain and skull

usually lethal

exact cause is not known

Question 25

Hirschsprungs disease?

Answer 25

A condition of the intestines that makes it difficult to pass stool due to the lack of innervation