This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Physiology
First change to occur in the distal segment of cut nerve: 
Select and explain. 
A. Myelin degeneration, B. Axonal degeneration, C. Mitosis of Schwann cell, D. Sprouting
B: Axonal degeneration
Answer: B: Axonal degeneration 
Explanation: After axotomy, the nerve terminals of the injured neuron begin to degenerate (first).