oligodendrocyte

Oligodendrocytes are a type of glial cell in the central nervous system that form and maintain the myelin sheath around axons. In the CNS, one oligodendrocyte extends multiple processes that wrap segments of several axons, creating myelin internodes separated by nodes of Ranvier. This insulation increases the speed of electrical signaling and reduces energy expenditure for axons. By contrast, Schwann cells in the peripheral nervous system myelinate single axons.

Oligodendrocytes originate from oligodendrocyte precursor cells (OPCs), which derive from neural progenitors during development. OPCs express PDGFRα and the surface proteoglycan NG2 and proliferate in response to PDGF. Differentiation into mature oligodendrocytes is driven by transcription factors such as Olig1/2, Sox10, and Myrf. Mature oligodendrocytes express myelin proteins including myelin basic protein (MBP), proteolipid protein (PLP), myelin-associated glycoprotein (MAG), as well as MOG and CNPase.

In myelinated CNS axons, the myelin sheath reduces membrane capacitance and increases conduction velocity via saltatory conduction. Oligodendrocytes also contribute to axonal metabolic support, delivering energy substrates through monocarboxylate transporters such as MCT1 and through gap junctions.

Clinical relevance: Demyelinating diseases such as multiple sclerosis involve loss or dysfunction of oligodendrocytes and myelin, leading to impaired conduction and neurological symptoms. Remyelination can occur via OPC recruitment and differentiation, but repair is often incomplete in chronic disease. Genetic defects in myelin proteins (for example PLP1) cause certain leukodystrophies.