Intracellular recordings from embryonic chick motoneurones in the isolated perfused spinal cord.

Potentials of 13- to 18-day chick embryo motoneurones were recorded intracellularly. Action potentials could be evoked by antidromic or direct stimulation of the cells, but the amplitudes were relatively low (less than 40-45 mV) and no overshoot or marked afterpotentials were observed. Pronounced evoked and spontaneous postsynaptic potentials were observed. Both irregular miniature and bursting high-voltage spontaneous postsynaptic depolarizations were present. The association of spontaneous action potentials with the latter type of spontaneous synaptic activity suggests its possible involvement in mechanisms of spontaneous embryonic motility.