Neural cells in culture

In vitro culture of neural cells (nerve sheath cells, melanoblasts, neuroblasts, astrocytes) for three to 20 months revealed a non-mitotic type of replication characterized by appearance between 30 and 120 days. Unipolar and bipolar neural cells, resulting from an initial phase of mitotic reproduction, developed multipolar and dendritic forms with large cell bodies and numerous primary and secondary processes with broad proximal ends exhibiting right-handed helices by phase contrast, differential interference electron microscopy and time lapse cinemicrophotography. The nuclei of the conspicuous cell bodies were quite large, one to three, and contained round, rod, ovid or comma nucleoli up to three or four per nucleus. After 30 days of culture, the nuclei of the cell bodies were notably quiescent with regard to mitotic proliferation, but nucleoli were active and mitochondria were numerous around the nuclei. The cytoplasm of the cell bodies often contained channels interpreted as cisternae of endoplasmic reticulum. The helices of the processes were interpreted as cytoplasmic pumps for conveying mitochondria into their distal ends. The slender distal ends became packed with rod and filamentous mitochondria, which then broke up into fine granules associated with the formation of new nuclei appearing in the preterminal and terminal ends of the processes. The preterminal or terminal unit--knob containing nucleus and distal end of process packed with mitochondrial dust--detached by was of a thread-like connection as a new cell, which entered into a new growth phase toward non-mitotic proliferation.