Identification of Cell Types in Neural Cultures

Tissue culture provides an opportunity to study the functions of the nervous system under strictly controlled conditions. As amply documented in other chapters in this volume, the culture medium, the surface upon which the cultures are growing, and various cellular and soluble factors can all modulate the growth and behavior of neural cells. A major variable in these cultures, however, remains the heterogeneity of the tissue used for the culture. Without knowing the relative proportions of neurons and glia, or the relative proportions of different subclasses of neurons, it can be difficult to interpret experimental results. If two types of electrophysiological responses are found under different growth conditions, is it because cell properties have become altered, or because different cell types are now present? If the amount of a particular neurotransmitter is altered by the addition of a certain growth factor, is it because the factor affected the synthesis, storage, or release of the transmitter, or because the proportion of cells utilizing this transmitter has altered?