Myelin formation in dissociated cell cultures of rat embryonic cerebral hemispheres.

Developing cultures of dissociated cerebral hemispheres obtained from 18-day-old embryonic rats synthesized, or activated, a myelin-related enzyme, 2',3'-cyclic nucleotide 3'-phosphohydrolase (CNPase). This increase in activity coincided with the onset of myelination. The presence of CNPase in oligodendrocytes and myelin was demonstrated using immunocytochemical staining techniques. Myelinated axons and myelin sheaths were clearly made visible by electron microscopy of 28-day-old cultures.