Competitive mechanisms underlying synapse elimination in the lumbrical muscle of the rat.

The process of neuromuscular synapse elimination has been studied in the fourth deep lumbrical (4DL) muscle of the rat, a preparation which offers technical advantages for some types of experimental work. Studies have been performed both during development and in adult denervated muscles undergoing reinnervation. Results indicate that synapse elimination is dependent upon competition between motoneurons. Cellular mechanisms underlying this competition have also been explored. Both neuromuscular activity and muscle fiber type recognition appear to play a role, but positional cues appear unimportant in this small muscle.