Genotype-specific myelin formation around normal axons in cytosine arabinoside-treated organotypic cultures injected with normal or shiverer optic nerve.

Organotypic cultures of newborn mouse cerebellum, treated with 'antimitotic' drugs to prevent myelination, contain abundant large neurons and axons but no mature oligodendroglia and no myelin. When oligodendroglia, contained in optic nerve fragments from 7-12-day-old normal or shiverer mutant mouse, are added to the cultures, myelin is formed in the vicinity of the optic nerve explant. The phenotype of the added myelin corresponds to the genotype of the optic nerve added, indicating that the added oligodendroglia are making the myelin themselves rather than contributing a diffusible factor which stimulates native cerebellar oligodendroglia or their precursors. This system will be valuable for direct, detailed comparisons of myelin formation by normal and mutant oligodendrocytes.