Precision of reinnervation of original postsynaptic sites in frog muscle after a nerve crush
Precision of reinnervation of original postsynaptic sites in frog muscle after a nerve crush
复制标题
神经挤压后青蛙肌肉原始突触后位点神经支配的精确度
DOI：
10.1007/bf01181582
复制
发表时间：
1976
期刊：
影响因子：
--
通讯作者：
Uel J. McMahan
中科院分区：
文献类型：
--
作者：
M. Letinsky;K. Fischbeck;Uel J. McMahan
摘要：在粉碎运动神经三个月后，用光镜和电子显微镜检查了青蛙皮胸肌中再生的神经肌肉连接。目的是确定原始突触位置的再神经支配的精度。超过95%的原始突触后膜被神经末梢恢复，几乎没有，如果有的话，在肌肉纤维表面的其他部分进行突触接触。即使在长时间的去神经支配后，当雪旺细胞从突触后膜上缩回70-80%时，再生终末仍会返回并覆盖大部分突触后膜。虽然突触局限于原始的突触位点，但肌纤维的神经支配模式在以下几个方面发生了改变：(a)再生的轴突终末不能分支，留下一小段突触后膜未被覆盖；(b)两个末端分支可以并排位于通常由一个末端占据的突触后膜上；(c)在沿着一根肌肉纤维的突触后膜生长后，末端可以离开它，在细胞外空间或在另一根肌肉纤维的突触后膜上结束。总之，这些结果表明，原始突触位点和再生神经末梢之间具有强烈的特异性亲和力。
SummaryRegenerating 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.