Neurocytology: Cells of the CNS

There are two major cell types that form the nervous system: supporting cells and conducting cells. The supporting cells of the peripheral nervous system consist of Schwann cells, fibroblasts, and satellite cells; the supporting cells in the central nervous system consist of the glia and the lining cells of the ventricles the ependyma (the meningeal coverings of the brain, the circulating blood cells, and the endothelial lining cells of the blood vessels). The conducting cells, or neurons, form the circuitry within the brain and spinal cord and their axons can be as short as a few microns or as long as 1 meter. The supporting cells are constantly being replaced, but the majority of conducting cells/neurons, once formed, remain throughout our life.