Wallerian degeneration

Question 1

Axonal injury

Answer 1

Cause - trauma
Axon is severed , disrupting ability it transmit signals this triggers molecular and cellular changes to initiate degeneration

Question 2

Axonal fragmentation

Answer 2

Time frame - 24 - 48 hours

Axonal cytoskeleton breaks down
Distal axonal segments, fragment into smaller pieces

Question 3

Myelin breakdown

Answer 3

Lyle in sheath break down into lipid rich debris
Schwann cells assist in clearing myelin debris

Question 4

Debris clearance

Answer 4

Schwann cells and macrophages move to injury site
Clearing the way for regeneration

Can take several weeks

Question 5

Proliferation of Schwann cells

Answer 5

Schwann cells proliferate and align to form regeneration tubes - they guide to help growth of new axonal sprouts from the proximal nerve stump

Question 6

Regeneration (if possible)

Answer 6

In case of axonotmesis - axonal sprouts grow along the bands
Reconnection to target organ

Question 7

What is it?

Answer 7

Wallerian degeneration is a process that occurs in peripheral nerves following an injury that disrupts the continuity of the axon, such as in axonotmesis or neurotmesis. It involves the degeneration of the distal portion of the axon and its myelin sheath, while the proximal segment remains intact and retains the potential for regeneration. This process is crucial for clearing damaged nerve tissue and creating an environment conducive to axonal regrowth