Glial cells were originally thought to play a very minor role in the nervous sys

Glial cells are known to play a number of roles in the nervous system. In the peripheral nervous system, Schwann cells form the myelin, or insulation, around the axons of motor or sensory neurons. They are also capable of helping to repair damage to these neurons. In the central nervous system, oligodendrocytes generate the myelin sheath. Astrocytes are found throughout the CNS, even wrapping around synapses. They regulate the extracellular environment and can help control levels of neurotransmitters at the synapse. Microglia also help maintain neurons by removing debris and dead cells from the CNS. Lastly, ependymal cells are found lining the ventricles of the brain, and use their cilia to move the cerebrospinal fluid through the cavities of the brain.