This page outlines information on glial cells.
Separate pages describe the nervous system in general and the central nervous system .
In the brain, the number of glial cells is 10-15 times greater than that of neurons. There are three types of glial cells in the CNS, the astrocytes, oligodendrocytes, and microglia. Microglial cells are part of the immune system and follow the characteristic actions and functions of that system. Astrocytes are involved in neurotransmission and in neuronal metabolism. Oligodendrocytes are involved in the production of myelin.