Much of the total volume of the brain and spinal cord is made up of cells that support nerve cells (neurons) in various ways but which don't carry information themselves. The collective name for these support cells is glial cells.
Glia comes from the Greek word for glue and one of the roles of these cells is to hold the nerve cells in place. Other functions include transporting nutrients to nerve cells and controlling the levels of neurotransmitters around synapses (astrocytes), cleaning up debris and digesting parts of dead neurons (astrocytes and microglia). Glial cells also provide insulation to neurons through the production of myelin, this is carried out by Schwann cells in the peripheral nervous system and oligodendrocytes in the central nervous system.
The specific glial cells that produce myelin in the central nervous system are called oligodendrocytes. Each oligodendrocyte can supply myelin for the axons of several nerve cells and each axon can be supplied by several oligodendrocytes. The myelin produced by oligodendrocytes wraps around the axons in thin sheets like a Swiss roll.
Last updated: December 2017
Last reviewed: March 2017
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