The differentiation of oligodendrocytes in the rat optic nerve

The time of appearance and the rate of accumulation of specific myelin lipids and proteins were measured in the rat optic nerve during the period from birth to 18 days. The appearance of the activities of several enzymes involved in the synthesis of these lipids was also monitored. Correlation of these biochemical data with previously known morphological findings indicated that the “active” oligodendrocytes (detected between 5 and 15 days after birth) displayed maximal levels of synthesis of the components of myelin, and that these cells appeared to be responsible for the initial synthesis of myelin. Both young and mature oligodendrocytes showed limited capacity to synthesize these compounds. Furthermore, induction of the enzymes involved in the synthesis of myelin components appeared to take place in a simultaneous, rather than a sequential manner.