Sakakima H, Kawamata S, Kai S, Ozawa J, Matsuura N
Institute of Health Sciences, Faculty of Medicine, Hiroshima University, Japan.
Arch Histol Cytol. 2000;63(5):495-506. doi: 10.1679/aohc.63.495.
The rat sciatic nerve was locally frozen, and changes in the nerve, motor endplates, and the soleus muscle were examined for up to 6 weeks by light and electron microscopy. The wet weights of denervated soleus muscles compared with contralateral values progressively declined to a minimum at 2 weeks after injury (60.7 +/- 2.5%) and began to reverse following 3 weeks. The sciatic nerve thoroughly degenerated after freezing. However, numerous regenerated myelinated and thin nerve fibers were observed at 3 weeks. They were considerably enlarged but still smaller than normal counterparts at 6 weeks postoperatively. Nerve terminals containing synaptic vesicles of endplates disappeared at day 1 and mostly reappeared at 3 weeks (about 70% of the endplates). All endplates examined were reinnervated at 4, 5, and 6 weeks. On the other hand, postsynaptic folds of muscle fibers seemed to be only slightly influenced by denervation or reinnervation. Ultrastructural alterations of myofibrils, in particular the loss of register, immediately appeared after denervation, spread progressively, peaked at 2 weeks, ameliorated following reinnervation, and became significantly normalized at 6 weeks after freezing. The proportion of type II fibers in the soleus muscle similary showed an increase and a decrease with a short delay in response to denervation and reinnervation, respectively. This study clearly demonstrated that the nerve supply affects the ultrastructural integrity of skeletal muscles. In addition, changes in the endplates and the soleus muscle evaluated in this study after short-term denervation are largely reversible following reinnervation.
将大鼠坐骨神经局部冷冻，通过光镜和电镜检查神经、运动终板和比目鱼肌长达6周的变化。去神经支配的比目鱼肌湿重与对侧相比，在损伤后2周逐渐下降至最低水平（60.7±2.5%），3周后开始恢复。冷冻后坐骨神经完全变性。然而，在3周时观察到大量再生的有髓神经纤维和细神经纤维。它们明显增粗，但在术后6周仍小于正常神经纤维。含有终板突触小泡的神经末梢在第1天消失，大部分在3周时重新出现（约70%的终板）。在4、5和6周时，所有检查的终板均重新获得神经支配。另一方面，肌纤维的突触后褶皱似乎仅受到去神经支配或重新神经支配的轻微影响。去神经支配后，肌原纤维的超微结构改变立即出现，尤其是肌节排列紊乱，逐渐扩散，在2周时达到峰值，重新神经支配后改善，冷冻后6周显著恢复正常。比目鱼肌中II型纤维的比例在去神经支配和重新神经支配后也分别出现增加和减少，且有短暂延迟。本研究清楚地表明，神经供应影响骨骼肌的超微结构完整性。此外，本研究中短期去神经支配后评估的终板和比目鱼肌的变化在重新神经支配后大多是可逆的。
