Which statement about Wallerian degeneration is true?

• A. Wallerian degeneration occurs in the proximal stump after injury.
• B. Wallerian degeneration occurs in the distal segment distal to the injury and may be followed by regeneration in the peripheral nervous system with Schwann cell guidance.
• C. Wallerian degeneration prevents any chance of recovery.
• D. Wallerian degeneration occurs in the CNS only.

Answer: (B)

Wallerian degeneration is the process where the part of the axon distal to the injury breaks down and is cleared away, while the proximal part can remain alive. In the peripheral nervous system, Schwann cells survive and organize to guide regenerating axons along the original pathways, using structures called Bands of Büngner to direct growth. This makes recovery possible if the environment is supportive and the distance to the target is not too great. In contrast, the central nervous system has more inhibitory factors and scarring that largely limit regeneration, which is why recovery is usually poorer there.

So the true statement describes degeneration occurring in the distal segment and notes that regeneration may occur in the peripheral nervous system with Schwann cell guidance. The other ideas are incorrect because degeneration happens distally, not at the proximal stump; it does not automatically rule out recovery; and it is not limited to the CNS.