True about Wallerian degeneration: (A) It is proximal degeneration, (B) Myelin sheath degeneration is the first change to occur, (C) It's a type of nerve regeneration, (D) None
Answer is D. Distal (Wallerian) degeneration: mediated by calcium influx and activation of axonal proteases 24 hours:neurofilaments break up and the axon fragments into sho lengths. Within 10 days:myelin decomposes into fat droplets (after 10 days, Schwann cells begins to fragment myelin sheath.....a change from myelinating to demyelinating) In 3 months: macrophages phagocytose the debris, leaving behind only endoneural tube/ ghost tube (filled by the rapidly multiplying Schwann cell's cytoplasm)