Sprouting and regression of neuromuscular synapses in partially denervated mammalian muscles.

摘要: 1. The capacity of motor units to sprout after partial denervation and the ability regenerating axons suppress newly formed sprouts was examined in mouse skeletal muscle. Most experiments were performed on peroneus tertius muscle which has 300 fibres eleven ranging strength from 1 35% total tension. 2. Individual units, regardless starting size, able by up 5 times their normal size following interruption one two spinal roots innervating In practive this resulted muscles had three or more left intact becoming completely innervated again within 12 days. majority probably old denervated end-plate sites. absence re-innervation severed persisted. about 60% giving rise end-plates arose terminally 40% collaterally. soleus almost all terminal. 3. Re-innervation occurred, 14 days onwards a crush injury, 19 cut. occurred even presumably no remaining at time reached re-innervating grew original 4. Following sprouted apparently decreased. Thus, with longer caused contraction However, state not restored continued innervate than normal, returning less small percentage (ca. 10%) remained functionally both sorts. 5. It is concluded that (i) mouse, axonal sprouting rapid efficient process for restoring innervation; (ii) already can occur if return existing sites; (iii) some redundant innervation removed repressed. 6. Possible mechanisms competition between axon terminals are considered.