Interaction with membrane remnants of target myotubes maintains transmitter sensitivity of cultured neurons.

Parasympathetic neurons, when cultured alone, lose sensitivity to acetylcholine, but if striated muscle is included in the culture, neuronal chemosensitivity is maintained. The membrane remnants of myotubes ruptured by osmotic shock also supported the responsiveness of the cultured neurons to transmitter, whereas muscle-conditioned medium or membrane remnants of nonmuscle embryonic skin cells did not support this responsiveness. The regulation of chemosensitivity by contact of neurons with the target cell membrane may be important in the formation and maintenance of neuronal circuitry.