Which tissue is made up of myelinated axons?

Which tissue is made up of myelinated axons?

• A. White matter
• B. Dorsal root
• C. Gray matter
• D. Anterior horns

Answer: (A)

White matter is composed mainly of myelinated axons, which form the long communication pathways that connect different parts of the CNS. The myelin sheath, made by oligodendrocytes in the CNS, wraps around axons and speeds up signal transmission through saltatory conduction. This abundance of myelinated axons gives white matter its characteristic color. In contrast, gray matter is rich in neuron cell bodies and unmyelinated processes, so it doesn’t appear white. The dorsal root is a peripheral nerve bundle of sensory axons (and their cell bodies lie in dorsal root ganglia), and the anterior horns contain motor neuron cell bodies—neither is tissue dominated by myelinated axon tracts like white matter.

White matter is composed mainly of myelinated axons, which form the long communication pathways that connect different parts of the CNS. The myelin sheath, made by oligodendrocytes in the CNS, wraps around axons and speeds up signal transmission through saltatory conduction. This abundance of myelinated axons gives white matter its characteristic color. In contrast, gray matter is rich in neuron cell bodies and unmyelinated processes, so it doesn’t appear white. The dorsal root is a peripheral nerve bundle of sensory axons (and their cell bodies lie in dorsal root ganglia), and the anterior horns contain motor neuron cell bodies—neither is tissue dominated by myelinated axon tracts like white matter.