Physiological and Pathological formation of the brain and spinal cord 14.02.23

Question 1

When does gastrulation occur?

Answer 1

3rd week

Question 2

What does the ectoderm become?

Answer 2

• Skin
• Nervous system

Question 3

What does the endoderm become?

Answer 3

• Epithelial lining of the gut and respiratory system
• Liver
• Pancreas

Question 4

What does the mesoderm become?

Answer 4

• Notochord
• Muscular system

Question 5

How does the neural plate form?

Answer 5

ectoderm thickens in midline

Question 6

What is the first part of the spine to form?

Answer 6

The neural plate

Question 7

How does the notochord form?

Answer 7

From mesoderm cells soon after gastrulation

Question 8

How does the notochord start folding to form neural tube?

Answer 8

• Signals from notochord cause inward folding of ectoderm at the neural plate
• End of neural plate fuse and disconnect to form a neural tube

Question 9

What are presumptive neural crest cells and where do they lie?

Answer 9

• They are presumptive because we don’t know exactly what they will become until they do
• They lie lateral to the neural groove
• Probably will form sensory ganglia, Schwann cells, adrenal medulla, meninges.

Question 10

What gives rise to Melanocytes, Schwann cells and neurons?

Answer 10

The ectoderm

Question 11

What gives rise to osteoblasts, adipocytes, chondrocytes?

Answer 11

The mesoderm

Question 12

What do the neural crest cells form?

Answer 12

• Dorsal root ganglia of spinal cord
• Schwann cells
• Adrenal medulla
• Meninges

Question 13

How do abnormalities of the spinal cord occur?

Answer 13

• Neural tube normally closes at end of 4th embryonic week
• Failure for this to close can cause neural tube defects

Question 14

What are the environmental factors that can cause neural tube defects?

Answer 14

• Folic acid
• Maternal diabetes
  (also can be family related)

Question 15

What are the embryological regions of the brain?

Answer 15

• Prosencephalon
• Mesencephalon
• Rhombencephalon
  (At 4 weeks)

Question 16

What does the prosencephalon give rise to?

Answer 16

The telencephalon at 6 weeks
- Each section will subdivide into other neurological regions and eventually permanent structures of the brain

Question 17

What does the prosencephalon become?

Answer 17

Cerebral hemispheres and thalamic structures

Question 18

What does the mesencephalon become?

Answer 18

Midbrain

Question 19

What does the rhombencephalon become?

Answer 19

• Becomes metencephalon and myelencephalon then…
• Medulla, pons, and cerebellum

Question 20

What happens to neurons in the ventricular zone?

Answer 20

Stem cells found here which give rise to neurons
- Neurons migrate to outer surface of brain and stop along the way where they are needed for that function
- Neurogenesis

Question 21

What is microcephaly and macrocephaly?

Answer 21

Micro: reduced head circumference
Macro: Increased HC

Question 22

Where does CSF circulate?

Answer 22

Through subarachnoid space and through ventricles

Question 23

What is the function of CSF?

Answer 23

Cushion the brain and help circulate metabolites away from brain

Question 24

How is CSF absorbed?

Answer 24

Via arachnoid granulations

Question 25

When does the development of sensation begin?

Answer 25

• Dermal skin innervated from 28 weeks

Question 26

When does the BBB develop?

Answer 26

Begins forming at 8 weeks

Question 27

How is the BBB formed?

Answer 27

From endothelial cells, pericytes and astrocytes

Question 28

When should neural tube close?

Answer 28

End of 4th week
If not results in: spina bifida