Synaptogenesis and myelinogenesis in dissociated cerebral cells from rat embryo on polylysine coated surfaces.

The appearance of myelinated axons and establishment of synaptic contracts in dissociated cells from rat embryo cerebral hemispheres grown on polylysine precoated surfaces were studied by light and electron microscopy. Typical myelin lamellae ensheathing axons were observed as early as the eighth day. Immature synaptic profiles exhibiting slight membrane thickening and few synaptic vesicles were observed after seven days. At 3 weeks, mature synapses containing many synaptic vesicles and the typical irregular membrane thickening could be seen. It is suggested that the presence of polylysine may provide a support which enhances the attachment and subsequent establishment of contacts between neuronal and glial cells, resulting in the early onset of myelin formation.