ON DIFFERENTIATION OF ISOLATED NERVE AND GLIA CELLS FROM TRYPSINIZED SPINAL CORD OF CHICKEN EMBRYOS CULTIVATED IN VITRO - A LIGHT- AND ELECTRONMICROSCOPICAL INVESTIGATION

Cervical and thoracic segments of the spinal cord of six and seven days old chicken embryos were trypsinized. The isolated cells have been cultivated in vitro and studied both light- and electronmicroscopically. Immediately after isolation, neurons or glial cells can not be distinguished by morphological criteria. After a few hours in vitro, however, the first sprouting of fibres is visible. About 12 hours later an aggregation of cells in bulks or loosely woven nets becomes more and more prominent, without an active cellmovement visible. The aggregational process of the previously dissociated cells is combined with ultrastructural differentiation. At the end of the first week in vitro one could recognize besides some astrocytes a great number of those cells which were neither astroglia-nor oligodendroglia-cells. The latter were not detectable during our short periods of cultivation. Those cells showing an enhancement of organelles and their endoplasmic reticulum formed an ergastoplasm after five to seven days in vitro are definitely nerve cells, whose axons and dendrites appear after three days of incubation. The most convincing criteria of nerve cell maturation is the appearance of synapses, which increase in number from the fifth day of incubation onwards. Axo-dendritic, axo-somatic and axo-axonal synapses are present. A possible physiological significance of the synapses in relation to their ultrastructural features and the importance of the membrane junctions" has been discussed. © 1969 Springer-Verlag Berlin Heidelberg."