Oligodendrocyte Myelination of Sensory Ganglion Neurites in Long Term Culture

Abstract

Oligodendrocytes of different ages were observed to combine with bare DRG neurons of variable embryonic ages. The myelin formed on the bare DRG neurites by oligodendrocytes showed several radial striation between myeline lamellae, which have been recognized as a tight junction in the CNS myelin in vivo. The myelin forming cells have no basal lamina on the surface of the cytoplesm. The optic nerve and corpus callosum of younger animals (of 1to 2 weeks postnatal) caused myelin to migrate markedly more than did the older oligodendrocytes (3 to 7 weeks). Surplus membrane-like materials were formed in the older oligodendrocytes without the ability of synthesizing myelin component. The lamination of myelin in the glial source from older animal was well preserved in long term culture after the loss of the axonal component. In the group of neurites including newly formed myelin, cellular construction was consistently observed; It was composed of one or two layers of fibroblasts on a collagen substrate, upon which were a few layers of astroglia, followed by groups of neurites and oligodendrocytes, which were occasionally covered by a few layers of fibroblasts. Basal lamina was associated with the astroglia and faced the lower layer of fibroblasts, or the collagen layer there were gaps in the fibroblasts.