GLIAL CELL TYPES
Astrocytes provide structural isolation of neurons and their synapses and provide ionic (K+) sequestration, trophic support, and support for growth and signaling functions to neurons. Oligodendroglia (oligodendrocytes) provide myelination of axons in the CNS.
Microglia are scavenger cells that participate in phagocytosis, inflammatory responses, cytokine and growth factor secretion, and some immune reactivity in the CNS. Perivascular cells participate in similar activities at sites near the blood vessels. Schwann cells provide myelination, ensheathment, trophic support, and actions that contribute to the growth and repair of peripheral neurons. Activated T lymphocytes normally can enter and traverse the CNS for immune surveillance for a period of approximately 24 hours.