[Emission of 2 axons by magnocellular neurons of the rat hypothalamus in culture].

The area of the supraoptic nucleus of young rats was cultured for several weeks using the roller-tube technique. Single cell recordings were then obtained with micropipettes filled with the fluorescent dye, lucifer yellow. This allowed intracellular recording of spike activity and the simultaneous ejection of dye for labelling of the cell soma, as well as its dendritic and axonal processes. Some one hundred injected neurones from thirty cultures were examined. A majority of these cells possessed a sizable cell body, 20-45 microns in diameter, from which 1-5 infrequently branching dendrites covered with few or no dendritic spines emerged. This morphology probably characterizes the magnocellular peptidergic neurones of the supraoptic nucleus. Very few of these cells were found to be dye-coupled to neighbouring neurones, but a fair proportion (approximately 10%) apparently gave rise to two axon-like processes.