Polyneuronal innervation of skeletal muscle in new‐born rats and its elimination during maturation.

作者：Michael C. Brown, Jan K. S. Jansen, David C. Van Essen · 发表于：The Journal of Physiology · 年份：1976 · DOI：10.1113/jphysiol.1976.sp011565 · 被引用次数：784 · 研究领域：Cerebral Palsy and Movement Disorders、Botulinum Toxin and Related Neurological Disorders、Mitochondrial Function and Pathology

1. The events taking place during the elimination of polyneuronal innervation in the soleus muscle of new-born rats have been studied using a combination of electrophysiological and anatomical techniques. 2. Each immature muscle fibre is supplied by two or more motor axons which converge on to a single end-plate. There was no sign of electrical coupling between muscle fibres receiving multiple synaptic inputs. By the end of the second week after birth virtually all muscle fibres are innervated by only a single motor axon. 3. The average tension produced by individual motor units, measured in terms of the percentage of the total muscle twitch tension, declined dramatically during the first 2 weeks after birth. During this period there was no significant change in the number of motor neurones innervating the soleus muscle. Thus, the disappearance of polyneuronal innervation reflects a decrease in the number of peripheral synapses made by each motor neurone. 4. The decline in motor unit size was delayed, but not ultimately prevented, by the early surgical removal of all but a few motor axons to the soleus muscle. This procedure also caused a delay in the removal of polyneuronal innervation involving the remaining motor units. 5. Following a crush of the soleus nerve in neonatal animals, regenerating axons usually returned to the original end-plates. Polyneuronal innervation was extensive at early stages of re-innervation and it disappeared during the second week after birth just...