Wallerian degenratin

Wallerian degeneration is the process where the part of the axon distal to a nerve injury degenerates. It occurs when part of the axon is disconnected from the neuron's cell body. A related process called Wallerian-like degeneration affects neurodegenerative diseases where axonal transport is impaired. Zenker's degeneration is severe muscle necrosis that can occur in prolonged fevers and involves death of muscle cell segments. Pyknosis is irreversible nuclear condensation in aging cells leading to fragmentation, while karyorrhexis is the destructive fragmentation of a dying cell's nucleus.