Synapse formation and induction of acetylcholine receptors by spinal neurones in cocultures with sympathetic ganglion and muscle cells.

Coculture of chick embryonic sympathetic neurones with spinal cord explants induced an age-dependent increase in the acetylcholine receptor numbers of the ganglion cells. These acetylcholine receptors did not appear to be necessary for the initial formation of spinal cord-ganglion synapses since their blockade with the alpha-bungarotoxin-horseradish peroxidase complex did not prevent synapse formation in culture. The presence of acetylcholine receptors appears to be sufficient for synapse formation since inappropriate motoneurone-ganglion synapses could form and were stable.