Kucera J
Cell Tissue Res. 1984;236(2):383-91. doi: 10.1007/BF00214242.
The motor nerve supply to cat nuclear bag1 intrafusal muscle fibers was reconstructed from light and electron microscopy of serial transverse sections of spindles in the tenuissimus muscle. Twenty-six of thirty poles of bag1 fibers that were examined received motor innervation. Every innervated bag1 pole received at least one (range 1-3) selective motor axon that supplied this fiber type only. Four of the innervated bag1 poles (15%) received additional motor supply from a nonselective motor axon that also innervated one nuclear chain fiber in the same spindle pole. The chain fibers co-innervated with bag1 fibers were among the longest chain fibers although they were shorter than two long chain fibers also present in the spindle poles. In cross-sections stained with toluidine blue they displayed 1-3 equatorial nuclei side by side, and there were fewer intermyofibrillar granules in their polar regions than in most of the other chain fibers. The endings of nonselective motor axons on the bag1 and chain fibers were morphologically and ultrastructurally dissimilar. It is suggested that instances of common innervation of the (dynamic) bag1 fiber and a (static?) chain fiber represent an integral and, presumably, functionally meaningful part of the motor pattern in some cat spindles.
通过对猫缝匠肌肌梭连续横切片的光学显微镜和电子显微镜观察，重建了猫核袋1梭内肌纤维的运动神经支配。在检查的30个袋1纤维极中，有26个接受了运动神经支配。每个受支配的袋1极至少接受一根（范围为1 - 3根）仅支配该纤维类型的选择性运动轴突。4个受支配的袋1极（15%）还接受了来自非选择性运动轴突的额外运动神经供应，该轴突也支配同一梭极内的一根核链纤维。与袋1纤维共同受支配的链纤维是最长的链纤维之一，尽管它们比梭极中另外两根长链纤维短。在用甲苯胺蓝染色的横切片中，它们并排显示1 - 3个赤道核，其极区的肌原纤维间颗粒比大多数其他链纤维少。非选择性运动轴突在袋1纤维和链纤维上的终末在形态和超微结构上不同。有人提出，（动态）袋1纤维和（静态？）链纤维的共同神经支配情况代表了某些猫肌梭运动模式中一个完整的、可能具有功能意义的部分。
