Knowledge of normal differentiations is indispensable for interpreting developmental disturbances in animal experiments. Accordingly, the investigations described in the present paper were aimed at explaining the process of myelinization of the optic nerve in the domestic mouse breed Agnes Bluhm Jena-Halle. First signs of myelin sheath formation can be seen on the sixth and seventh day post partum. The myelin sheath grew considerably up to the 20th day of life; under light microscopic examination this process was seen to end on approximately the 30th day post partum. Electron-microscopic examination provided proof that myelinization is effected by the oligodendrocytes. This process of differentiation continues even in the adult animal, though on a very small scale.
Animals Astrocytes