The myelination of axons by oligodendrocytes in the central nervous sy
stem and Schwann cells in the peripheral nervous system is essential f
or the establishment of saltatory conduction. Ln the absence or destru
ction of the myelin sheath, as seen in demyelinating diseases, impulse
conduction is impeded resulting in severe sensory and motor deficits.
Axon myelination is the culmination of a sequence of events that begi
ns with the differentiation of glial cells and proceeds to the transcr
iption and translation of myelin genes, the elaboration of a myelin sh
eath, and the recognition and ensheathment of axons. This review exami
nes the regulatory mechanisms for each of these steps and compares and
contrasts the role of the axon in initiating myelination in the centr
al and peripheral nervous system.