Which glial cell primarily forms myelin in the central nervous system?

• A. Astrocytes
• B. Oligodendrocytes
• C. Microglia
• D. Schwann cells

Answer: (B)

Oligodendrocytes form myelin in the central nervous system. These glial cells extend their processes to wrap around multiple axons, creating myelin sheaths that electrically insulate the axons. This insulation speeds up signal transmission through saltatory conduction, allowing impulses to jump from node to node along the axon. In contrast, Schwann cells perform myelination in the peripheral nervous system, wrapping a single axon segment each. Astrocytes support neurons and regulate the environment, while microglia act as immune-like cells that remove debris. So the cells responsible for CNS myelin are oligodendrocytes.