Three cholinergic neuroblastoma hybrid cell lines that form few synapses on myotubes are deficient in acetylcholine receptor aggregation molecules and large dense core vesicles.

Three neuroblastoma X glioma hybrid cell lines that synthesize and release acetylcholine but that form few or no synapses with cultured skeletal muscle cells lack two characteristics of neuroblastoma or hybrid cell lines that do form many synapses with myotubes: large dense core vesicles and the ability to increase the number of nicotinic acetylcholine receptor clusters on co-cultured myotube membranes. Functional synapse formation on myotubes was increased by co-culturing myotubes and cells from one of the defective lines with neuroblastoma cells that induce myotube acetylcholine receptor aggregation but which synthesize little or no acetylcholine.