The electron-microscopic picture of postnatal development of oligodendroglia.

Ultrastructural studies were carried out on the oligodendroglia in the corpus callosum of rat brain in different periods of the animal's extrauterine development. These investigations showed a possibility of distinguishing in the early stages of ontogenesis three forms of oligodendroblasts differing from one another by electron density and the organelle content of the cytoplasm. The beginning of the production of medullary sheaths was noted as early as the first day after birth and the termination of the morphological phase of this process was recorded on the 8th day of postnatal ontogenesis. Moreover, it was found that on the 17th day of the rat's life the process of differentiation of oligodendroglia in the corpus callosum comes to an end.