Chapter 7 - Peripheral glia physiology and function

Abstract

Peripheral glia are a heterogenous group of neural cells that are united by their neural crest origin and their restricted occupation of the peripheral nervous system (PNS) and absence from the central nervous system (CNS), with the exception of olfactory ensheathing cells, which occupy both the central and peripheral nervous systems. The major types of peripheral glia are Schwann cells, which myelinate and ensheath peripheral axons, as well as associating with motor and sensory axons at their terminals. In addition, neurones within sensory and autonomic peripheral ganglia are enwrapped by satellite glia. In the gastrointestinal tract, enteric glia encompass ganglion cells of the enteric nervous system plexuses that control gut motility, while other enteric glia interact with the mucosal lining of the gut. Peripheral glia perform diverse functions depending on their location, ranging from myelination to ensure rapid saltatory conduction of nerve impulses, the formation and function of synapses, nociception, regulation of gastrointestinal motility and barrier functions of peripheral nerves, the intestinal epithelial barrier and the skin. In addition, peripheral glia support neuronal regeneration and ensure recovery of function, which is critical considering the continuous everyday minor damage that peripheral neurones are exposed to during the lifespan, such as cuts and wounds that are repaired fully in the periphery, but have irreversible effects in the CNS. The heterogeneity of peripheral glia reflects their diverse functions in maintaining all bodily functions.