The characteristic sequence of changes that occurs in a vertebrate sensory or motor peripheral neuron after its axon has been severed. The cut length of axon now separated from the cell body degenerates, and associated Schwann cells dedifferentiate and proliferate and—with invading macrophages—phagocytose the remnant axon and myelin sheath. The cell body swells, the nucleus moves from a central to a more peripheral location, and the prominently staining endoplasmic reticulum (see nissl granules) becomes dispersed. Within hours, new axonal sprouts emerge from the axon stump and start growing towards their target within the basal lamina that ensheathed the original axon. The process is named after British physiologist Augustus Waller (1816–70).