Brain cells in culture. Fluorescent light micrograph of a microglial cell (upper left) and an oligodendrocyte (centre) from a human brain. Microglia are involved in immune reactions in the central nervous system (CNS), where they recognise areas of damage and inflammation and phagocytose (engulf) cellular debris. Oligodendrocytes form the myelin sheath around neurons (nerve cells) in the CNS. The sheath insulates the axon of each nerve cell, allowing efficient transmission of electrical impulses.
