In the CNS, oligodendroglia provide myelin for myelinated axons. In the PNS, Schwann cells provide myelin for myelinated axons. Hence all axons in nerves are associated with Schwann cells. Synaptic vesicles are always found in the pre-synaptic side of the synapse and provide a clue to the direction of information transfer for any synapse. Neuronal structure reflects neuronal function.
Microglia are macrophages that become phagocytic upon injury to nervous system.
They migrate into the developing nervous system. Macroglia Astrocytes are star-shaped cells characterized by a special class of intermediate filaments and terminal expansions of cell processes that adhere to blood vessels. Protoplasmic Astrocytes are found in grey matter and they have more cytoplasm and fewer intermediate filaments. Oligodendroglia are glial cells found in both white and grey matter. Ependymal Cells are epithelial cells lining the ventricles of the brain and the spinal canal.