Oligodendroglia

Oligodendroglia, also called oligodendrocytes, are the glial cells of the central nervous system responsible for forming and maintaining the myelin sheaths that wrap around axons. In the CNS, myelin increases the speed of electrical signaling and helps preserve axonal integrity. One oligodendrocyte can extend multiple processes to myelinate segments on several different axons.

Origin and development: Oligodendrocytes arise from oligodendrocyte precursor cells (OPCs) that originate in the developing neural tube. OPCs migrate throughout the CNS and differentiate into mature oligodendrocytes during fetal development, continuing in some regions after birth. OPCs commonly express markers such as PDGFRα and NG2, while mature oligodendrocytes express myelin-related proteins including MBP, PLP, and MOG.

Structure and function: Oligodendrocytes wrap their membranes around axons to form multilayered myelin sheaths. The myelin sheath increases conduction velocity via saltatory conduction and provides metabolic support to axons, in part through transport of nutrients. In the CNS, each oligodendrocyte can myelinate multiple axons, though individual axonal segments are myelinated by distinct oligodendrocyte processes.

Distribution and interactions: Oligodendrocytes are most abundant in white matter but are also present in gray matter. They interact with neurons, astrocytes, and microglia and contribute to myelin turnover and repair processes in response to injury or disease.

Clinical relevance: Demyelinating diseases such as multiple sclerosis involve loss or damage to oligodendrocytes and subsequent myelin degeneration, impairing neural conduction. Remyelination can occur via oligodendrocyte precursor cells, but efficiency declines with aging. Hereditary leukodystrophies (for example, Pelizaeus–Merzbacher disease) reflect genetic defects affecting oligodendrocyte function and myelin formation.