Which cell type wraps axons in a myelin sheath in the CNS?

Which cell type wraps axons in a myelin sheath in the CNS?

• A. Wraps axons in a myelin sheath
• B. Small; Least numerous
• C. Line cavities with CSF
• D. Contains nucleus

Answer: (A)

In the CNS, myelination is done by oligodendrocytes. These glial cells extend processes that wrap around multiple axons, laying down concentric layers of membrane to form the myelin sheath. This insulation increases conduction velocity along the axon by enabling saltatory conduction at the nodes of Ranvier. Schwann cells perform a similar wrapping task in the peripheral nervous system, but they myelinate only a single axon segment. The other options describe different cell roles (lining brain ventricles with CSF or just noting a nucleus) and don’t address CNS myelin formation.

In the CNS, myelination is done by oligodendrocytes. These glial cells extend processes that wrap around multiple axons, laying down concentric layers of membrane to form the myelin sheath. This insulation increases conduction velocity along the axon by enabling saltatory conduction at the nodes of Ranvier. Schwann cells perform a similar wrapping task in the peripheral nervous system, but they myelinate only a single axon segment. The other options describe different cell roles (lining brain ventricles with CSF or just noting a nucleus) and don’t address CNS myelin formation.