シュワン細胞
A cut axon in the peripheral nervous system has two parts: a distal and a proximal axon stump. The space in between the two stumps is known as the gap, and is what the nerve must grow through in order to fully regenerate and reinnervate. The distal axon is degenerated through the body's own mechanisms, mostly macrophage consumption and enzymes breaking it down. The proximal part of the cut axon is many times able to regenerate. The regeneration and reinnervation of the cut nerve is affected by multiple factors, including how far the nerve must regrow, what kind of environment it is growing in, and the different Schwann cells and pathway options available. PMR indicates that a regenerating motor neuron will choose a motor pathway Schwann cell over a cutaneous pathway Schwann cell when regenerating.