Answer
A single Schwann cell myelinates a single axon, but a single oligodendrocyte is able to myelinate more than one axon..
Work Step by Step
Schwann cells are one of the two types of glial cells in the PNS. Satellite cells provide structural support for neurons and aid in exchange of materials between neurons and the interstitial fluid. Myelination is carried out by Schwann cells. Each Schwann cell may wrap as many as 100 layers of membrane around a single axon. The outer part of this wrapping constitutes the neurolemma ( not found in (CNS); the inner layers form the myelin sheath. Myelination is discontinuous along myelinated axons (both in the PNS and in the CNS). The gaps in the myelin sheath are called Nodes of Ranvier.
The lipoid myelin covering effectively insulates the axons, so that nerve impulses can travel along myelinated nerves only by jumping from node to node. This so-called saltatory conduction speeds up neural transmission; as a result, nervous conduction along myelinated nerves is much faster than along unmyelinated nerve fibers.
Oligodendrocytes are the glial cells that carry out myelination of CNS axons. There are Nodes of Ranvier in the CNS myelin sheath also, but there is no neurolemma. Conduction in the CNS is also by the saltatory mode.
