Reinnervation of muscle fiber basal lamina after removal of myofibers. Differentiation of regenerating axons at original synaptic sites.
Reinnervation of muscle fiber basal lamina after removal of myofibers. Differentiation of regenerating axons at original synaptic sites.
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DOI：
10.1083/jcb.78.1.176
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发表时间：
1978-07
期刊：
影响因子：
--
通讯作者：
McMahan UJ
中科院分区：
文献类型：
--
作者：
Sanes JR;Marshall LM;McMahan UJ
轴突再生，准确地在原始突触位置重新支配失神经的骨骼肌纤维，并分化为神经末梢，在那里它们与肌肉纤维接触。本研究的目的是确定影响再生轴突生长和分化的因素的位置。我们损伤并去神经支配青蛙肌肉，导致肌纤维和神经末梢退化，然后对动物进行辐射，以防止肌纤维再生。包围着每个肌纤维的基底板鞘在这些治疗中存活下来，在神经末梢和肌细胞完全去除后，基底板上的原始突触位置可以通过几个组织学标准来识别。2周内轴突再生进入损伤区。它们几乎完全在原始的突触部位与存活的BL接触；因此，指导轴突生长的因素存在于突触部位，并稳定地维持在肌纤维之外。接触BL的部分轴突获得活动区并积累突触小泡；因此，根据形态标准，它们分化为神经末梢，即使它们的突触后目标--肌纤维--不存在。在终末内，突触细胞器在肌纤维的BL中排列成相反的周期性特化，表明与BL相关的成分在组织神经末梢的分化中发挥了作用。
Axons regenerate to reinnervate denervated skeletal muscle fibers precisely at original synaptic sites, and they differentiate into nerve terminals where they contact muscle fibers. The aim of this study was to determine the location of factors that influence the growth and differentiation of the regenerating axons. We damaged and denervated frog muscles, causing myofibers and nerve terminals to degenerate, and then irradiated the animals to prevent regeneration of myofibers. The sheath of basal lamina (BL) that surrounds each myofiber survives these treatments, and original synaptic sites on BL can be recognized by several histological criteria after nerve terminals and muscle cells have been completely removed. Axons regenerate into the region of damage within 2 wk. They contact surviving BL almost exclusively at original synaptic sites; thus, factors that guide the axon's growth are present at synaptic sites and stably maintained outside of the myofiber. Portions of axons that contact the BL acquire active zones and accumulations of synaptic vesicles; thus by morphological criteria they differentiate into nerve terminals even though their postsynaptic targets, the myofibers, are absent. Within the terminals, the synaptic organelles line up opposite periodic specializations in the myofiber's BL, demonstrating that components associated with the BL play a role in organizing the differentiation of the nerve terminal.