Fine structure of Periplaneta americana neurons in long-term culture

A new culture technique is described for dissociated ganglia of embryos of Periplaneta americana. Neurons obtained by the mechanical dissociation of ganglia from 23-26 day old embryos were grown for seven days in a combination of Schneider's Drosophila Medium and Eagle's Basal Medium and then transferred to a combination of Leibovitz's L-15 Medium and Yunker's Modified Grace's Medium supplemented with ecdysone. Neurons cultured in this way survived for periods in excess of one month. The cells had a typically neuronal ultrastructure and produced axonal processes that associated to form fibre bundles. Within these processes neurosecretory granules, dense-core vesicles and clear vesicles were found. In some instances these vesicles aggregated at points of contact between fibres giving the appearance of presynaptic endings. These cultures would appear to be suitable for pharmacological studies of the insect nervous system.