Who Is Who among Glial Cells?
Glial cells are classified in two main groups: microglia and macroglia. Microglia are macrophage-like cells that regulate the inflammatory response of the neural tissue to injury or infection. Macroglia are subdivided in four specialized cell types: ependymal cells, Schwann cells, oligodendroglia, and astroglia. Ependymal cells line the cerebral ventricular cavities and the central canal of the spinal cord and are in direct contact with the cerebrospinal fluid. Schwann cells and oligodendroglia are responsible for the formation of myelin, an essential component facilitating action potential propagation. Schwann cells form the myelin in the peripheral axons and oligodendroglia in central axons. In addition, both cell types regulate axonal excitability. Astroglia refers to a heterogeneous population that includes astrocytes, marginal glia, radial glia in the developing brain, Bergmann cells in the cerebellar cortex, Müller cells in the retina, pituicytes in the neurohypophysis, and tanyc
