Morphological maturation and survival of chicken and rat embryonic neurons on different culture substrata

Abstract

Neuronal cells from chicken and rat embryonic cerebral hemispheres were plated at a low cell concentration and cultured either on collagen or on a supporting continuous glial layer for periods of up to 21 days. The glial layer was either homologous or heterologous with regard to the animal species; the survival and maturation of the neuronal cells in these different conditions were investigated by light and electron microscopy.Neuronal cells cultured on collagen formed aggregates similar to those formed by neuronal cells plated at high cell density as described in a previous paper; a few aggregated neurons formed processes after 24 h and, only after 48 h of culture, more fibres had developed; the majority of the cells progressively degenerated between days 7 and 21 of culture. In contrast to this, neuronal cells cultured on a supporting glial layer, whether homologous or heterologous, progressively differentiated: neuronal perikarya remained well separated from each other and many processes were already formed after 24 h; later on, networks of fibres developed. At the electron microscopic level, microtubules and neurofilaments were present at a high density in the cells and fibres; immature synapses could be found, but infrequently. Differentiated cells were represented mostly by neurons; oligodendroglial cells were absent, and myelinated fibres could not be detected.The highest positive effect on the maturation and survival of neuronal cells was observed in the presence of a layer of glial cells from the same species. These results emphasize the essential role of glial cells for the neuronal maturation in the absence of contact between neuroblasts.