Which cells provide myelination to the optic nerve?

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

Answer: (A)

The optic nerve is part of the central nervous system, and its myelin is formed by oligodendrocytes. These glial cells wrap their processes around multiple axons to create a myelin sheath, which speeds up electrical conduction through saltatory conduction. In the eye, nerve fibers are unmyelinated while they reside in the retina, but once they exit and travel through the optic nerve, oligodendrocytes take over the myelination. Schwann cells cover axons in the peripheral nervous system, so they aren’t responsible for myelin in the optic nerve. Astrocytes support neurons and help maintain the environment, while microglia are immune cells; neither forms the myelin sheath. In diseases like multiple sclerosis, demyelination of CNS fibers—including the optic nerve—highlights the role of oligodendrocytes in CNS myelination.