Oligodendrocytes – Location, Structure, and Function

Author: Scott A. Sheffield MS

Last update: Oct 12th, 2022

A type of support cell found in the spinal cord and brain (central nervous system, CNS) is the oligodendrocyte.

• As its name implies, an oligodendrocyte is a cell (cyte) with a relatively small number (oligo) of cytoplasmic processes that branch (dendro) from a spherical cell body.

• The tip of each cytoplasmic process repeatedly wraps around a nearby axon to form a lipid-rich myelin sheath measuring about 1 millimeter in length.

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• Oligodendrocytes thus function much like Schwann cells do in the peripheral nervous system.
• However, oligodendrocytes have multiple cytoplasmic processes and myelinate several (up to 50) axons at the same time.

• As in the PNS, the narrow gaps between myelin sheaths are called nodes of Ranvier, and action potentials (electro-chemical impulses) occur only in these unmyelinated regions of the axon.

• The jumping of action potentials from node to node (saltatory conduction) increases the rate at which signals move down the axon.

• Because lipids are light in color, they make myelinated axons appear white in their natural (unstained) state.
• The regions of the CNS that contain high concentrations of myelinated axons are thus referred to as white matter.