Which cells are primarily responsible for the insulation of nerve fibers in the central nervous system?

Oligodendrocytes are the cells primarily responsible for the insulation of nerve fibers in the central nervous system. These cells extend their processes to multiple axons, wrapping around them to form the myelin sheath, which is crucial for the rapid transmission of electrical signals along the nerve fibers. Myelination increases the speed of action potentials through a process called saltatory conduction, where the impulse jumps from one node of Ranvier to another, significantly enhancing the efficiency of nerve signal conduction.

In contrast, astrocytes, while important for supporting neurons and maintaining the blood-brain barrier, do not provide the insulation of axons. Nerve endings are the terminals of neurons that release neurotransmitters but do not participate in myelination. Schwann cells, unlike oligodendrocytes, are responsible for myelinating nerve fibers in the peripheral nervous system, not the central nervous system. Thus, oligodendrocytes are specifically tailored to the requirements of the central nervous system's neuronal insulation.