Regional differences in the timing of synapse elimination in skeletal muscles of the neonatal rabbit.

The time course of disappearance of polyneuronal innervation during development was studied electrophysiologically in skeletal muscles of the rabbit. There were differences of up to a week in the estimated time of onset of synapse elimination in various muscles, with a tendency for the process to begin earlier in muscles situated more anteriorly in the body. There were also differences among muscles in the peak rate of synapse loss during maturation, but these differences do not appear to be related to position in the body or to contractile properties of the muscle.