猫运动神经末梢的形态和长芽:快肌与慢肌间的不同

MORPHOLOGY AND SPROUTING OF MOTOR NERVE TERMINALS IN CAT:DIFFERENCES BETWEEN FAST AND SLOW MUSCLES

用锌碘化合物-锇酸染色法显示猫肌肉中的运动神经末梢(或终板),报道4只正常成年猫两侧后肢的快肌(外侧头腓肠肌、内侧头腓肠肌)和慢肌(比目鱼肌)4,307个终板观察的结果。快肌和慢肌运动神经末梢的形态明显不同。外侧头腓肠肌和内侧头腓肠肌的运动神经末梢分支多而细,形成圆形或椭圆形;比目鱼肌的运动神经末梢分支少而粗,形成长圆形或不规则形。外侧头腓肠肌和内侧头腓肠肌中,T_(2)型和T_(3)型运动神经末梢较多,为16~66%;比目鱼肌中则少于10%。末梢长芽的情况也不同,末梢前芽在外侧头腓肠肌和内侧头腓肠肌中的平均值各为8.5±5.4%、7.1±3.2%;比目鱼肌中为0.3±0.5%。末梢端芽在外侧头腓肠肌和内侧头腓肠肌中的平均值各为0和0.3±0.5%;比目鱼肌中为5.7±2.0%。每块外侧头腓肠肌、内侧头腓肠肌或比目鱼肌都有大有小,分支有多有少;并且还有变性的和长芽的各种不同形态。此外,本文还讨论了影响运动神经末梢形态的可能因素。

Motor nerve terminals of fast muscles(lateral head of gastrocnemius,l.g.medial head of gastrocnemius,m.g.)and slow muscles(soleus,sol.)in 4 healthy adult cats were studied in teased muscle fibres with zinc iodide-osmium tetroxide(ZIO)staining.The motor nerve terminals stained with ZIO had a more delicate appearnance than those stained with other methods.It was obvious that fairly marked differences between the strutures of fast and slow muscle end-plate in cat.The terminal sprouts were also different between fast and slow muscle motor nerve terminals.in cat.The percentages of preterminal sprout were mean%±S.D.8.5±5.4,7.1±3.2 and 0.3±0.5 in l.g.,m.g,and sol.respectively,and the percentages of ultraterminal sprout were 0,0.3±0.5 and 5.7±2.0 in l.g.,m.g.and sol.respectively.In each l.g.,m.g.or sol.muscle,not only the size and complexity of end-plates were different,but also there were various kinds of end-plates.All of these showed the different stages of growth,sprouting,degeneration and replacement.The turnover of motor nerve terminal and the factors which influence the morphology of the end-plates in normal adult cat are discussed.