Schwann Cell

The Schwann cell is a support cell of the peripheral nervous system. They wrap around each motor neuron axon of the peripheral nerve fibers, producing the myelin sheath that protects this long nerve cell process. Thus, this support cell is the equivalent to the oligodendrocyte of the central nervous system. However, Schwann cells also have phagocytic function, like the microglia in the brain, in response to nerve injury and inflammation. Function: to produce the myelin that covers and protects the axon. Myelin, which is a fatty layer that insulates the axon, helps to increase the saltatory conduction of the neuron.

Unlike the cells that make up the neuroglia, the Schwann cells secrete collagen, laminin, and fibronectin, which are extracellular adhesive proteins. These proteins are the constituent elements of the basal lamina, extraneuronal matrix, and the basement lamina that envelops the cell membrane of axons. Since the Schwann cell wraps around the peripheral neuron axon, it is effective in isolating their immediate environment from the extraneuronal space.

The Schwann cell is limited in length. Therefore, a long motor neuron axon is covered by thousands of these support cells. At the node of Ranvier -which is the point where one myelinating Schwann cell ends and another begins- the axon is exposed to the fluids and ions surrounding it. Unmyelinated nerve fibers of the peripheral nervous system are associated with Schwann cells in a different way than myelinated nerve fibers. In this case, axons from several unmyelinated fibers are embedded in each Schwann cell, but here it does not produce myelin.

Summary

The Schwann cell plays a vital role in maintaining the peripheral nervous system (PNS). Schwann cells are derived from neural crest cells, and come in two types either myelinating or non-myelinating Schwann cells. Both play an important role in the maintenance and regeneration of axons of the neurons in the PNS. The regulation of Schwann cells is mediated a number of different neurotrophic factors. The Schwann cell plays a vital role in maintaining the peripheral nervous system (PNS). Schwann cells are derived from neural crest cells, and come in two types either myelinating or non-myelinating Schwann cells. Both play a pivotal role in the maintenance and regeneration of axons of the neurons in the PNS. The regulation of Schwann cells is mediated a number of different neurotrophic factors.