Letinsky M S, Fischbeck K H, McMahan U J
J Neurocytol. 1976 Dec;5(6):691-718. doi: 10.1007/BF01181582.
Regenerating neuromuscular junctions in the cutaneous pectoris muscle of the frog were examined by light and electron microscopy up to three months after crushing the motor nerve. The aim was to determine the precision of reinnervation of the original synaptic sites. More than 95% of the original postsynaptic membrane is recovered by nerve terminals and little, if any, synaptic contact is made on other portions of the muscle fibre surface. Even after prolonged denervation when the Schwann cells have retracted from 70-80% of the postsynaptic membrane, regenerating terminals return to and cover a large fraction of it. Although synapses are confined to the original synaptic sites, the pattern of innervation of muscle fibres is altered in several ways: (a) regenerating axon terminals can fail to branch leaving small stretches of postsynaptic membrane uncovered; (b) two terminal branches can lie side by side over a stretch of postsynaptic membrane normally occupied by one terminal; and (c) after growing along a stretch of postsynaptic membrane on one muscle fibre, terminals can leave it to end either in extracellular space or on the postsynaptic membrane of another fibre. Altogether the results demonstrate a strong and specific affinity between the original synaptic sites and regenerating nerve terminals.
在蛙胸皮肌中，对运动神经挤压后长达三个月的时间内，通过光学显微镜和电子显微镜检查了再生的神经肌肉接头。目的是确定原始突触部位再支配的精确性。超过95%的原始突触后膜被神经末梢重新占据，在肌纤维表面的其他部位几乎没有形成突触联系。即使在长时间去神经支配后，当施万细胞从70 - 80%的突触后膜退缩时，再生的神经末梢仍会返回并覆盖其中大部分。尽管突触局限于原始突触部位，但肌纤维的神经支配模式在几个方面发生了改变：(a)再生的轴突末梢可能无法分支，使一小段突触后膜未被覆盖；(b)两个末梢分支可能并排位于通常由一个末梢占据的一段突触后膜上；(c)在沿着一根肌纤维的一段突触后膜生长后，末梢可能离开该膜，终止于细胞外空间或另一根纤维的突触后膜上。总的来说，这些结果表明原始突触部位与再生神经末梢之间存在强烈而特异的亲和力。
