Which glial cell forms the myelin sheath in the CNS?

Which glial cell forms the myelin sheath in the CNS?

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

Answer: (B)

Oligodendrocytes form the myelin sheath in the central nervous system. These glial cells extend their membrane processes to wrap around segments of axons, laying down multiple layers of myelin. A single oligodendrocyte can myelinate portions of several different axons, which speeds signal conduction through saltatory conduction with gaps known as nodes of Ranvier. In contrast, Schwann cells in the peripheral nervous system myelinate a single segment of one axon, astrocytes support neuronal function and the blood-brain barrier, and microglia act as immune cells.

Oligodendrocytes form the myelin sheath in the central nervous system. These glial cells extend their membrane processes to wrap around segments of axons, laying down multiple layers of myelin. A single oligodendrocyte can myelinate portions of several different axons, which speeds signal conduction through saltatory conduction with gaps known as nodes of Ranvier. In contrast, Schwann cells in the peripheral nervous system myelinate a single segment of one axon, astrocytes support neuronal function and the blood-brain barrier, and microglia act as immune cells.