Patterning of skeletal muscle.

Recent studies challenge the view that signals provided by motor neurons are required to activate subsynaptic nuclei and induce postsynaptic specializations in developing skeletal muscle. New findings show that acetylcholine receptor genes are expressed and that acetylcholine receptor clusters form preferentially in the prospective synaptic region of muscle independently of motor innervation. These results indicate that developing myotubes are patterned by mechanisms intrinsic to developing muscles and raise the possibility that patterning of muscles may influence the growth pattern of motor axons and the sites where synapses form.