In a Wallerian degeneration injury, which histological change occurs in the proximal nerve stump that is essential for successful nerve regeneration?

• A Schwann cells undergo apoptosis and are cleared, leaving an empty endoneurial tube
• B Schwann cells in the distal stump proliferate to form Bands of Büngner that guide regenerating axon sprouts ✓
• C Macrophages lay down a collagen matrix in the distal stump to provide a scaffold
• D Satellite cells from muscle migrate into the nerve to facilitate re-innervation

Explanation

After axonal injury causing Wallerian degeneration, Schwann cells in the DISTAL stump undergo dedifferentiation and proliferation, forming longitudinal cellular columns called Bands of Büngner within the intact endoneurial tubes. These Schwann cell columns express neurotrophic factors (NGF, BDNF, GDNF) and adhesion molecules that guide and support regenerating axon sprouts growing from the proximal stump at 1-2 mm/day. This is the essential scaffold for peripheral nerve regeneration. Schwann cells do not undergo apoptosis; macrophages phagocytose myelin debris. The key cell is the Schwann cell of the distal stump.

Reference: Maheshwari Essential Orthopaedics, 6th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.