Regeneration

Question 1

How do astrocytes act to inhibit axonal growth?

Answer 1

• secrete inhibitory chondroitin sulphate proteoglycans

- form a cyst that forms a physical barrier preventing axonal growth

Question 2

What is NOGO?

Answer 2

Myelin protein found in the CNS that is thought to inhibit axon regeneration in the CNS

Question 3

What are the objections to NOGO inhibiting axon regeneration>

Answer 3

• no correlation between NOGO/NOGO receptor levels and regenerative capacity
• transplanted hippocampal neurons grow axons into myelin
• a lot of myelin is removed by macrophages after damage
• poor regeneration in grey matter (not a lot of myelin)

Question 4

what signals trigger Xenopus tail regeneration?

Answer 4

BMPs

Question 5

DEFINE: endoneurium

Answer 5

connective tissue surrounding fascicles

Question 6

DEFINE: perineurium

Answer 6

connective tissue surrounding many fascicles and blood vessels bundled together

Question 7

DEFINE: epineurium

Answer 7

connective tissue surrounding nerve

Question 8

DEFINE: neuropraxia

Answer 8

nerve damage caused by compression or stretching of nerve
myelin and schwann cells may be damaged
blocks conduction

Question 9

DEFINE: axonotmesis

Answer 9

complete interruption of axon + myelin sheath

connective tissue still infact

Question 10

DEFINE: neurotmesis

Answer 10

complete cut of nerve

Question 11

what are the effects of denervation on muscle?

Answer 11

muscle atrophy
reversal of AChR into embryonic AChR
upregulate MuSK
= muscle dedifferentiation

Question 12

What is sufficient to prevent muscle atrophy?

Answer 12

External electrical input

Question 13

How do peripheral nerves regenerate?

Answer 13

1. mitosis of schwann cells
2. schwann cells form bands of bungner = rows of schwann cells providing scaffold for axon guidance
3. axon grows along dividing schwann cells into distal stump
   intact neighbouring fibre sprouts to reinnervate damaged nerve