Wokke J H, Jennekens F G, van den Oord C J, Veldman H, Smit L M, Leppink G J
Laboratory of Neuromuscular Diseases, University of Utrecht, The Netherlands.
J Neurol Sci. 1990 Mar;95(3):291-310. doi: 10.1016/0022-510x(90)90076-y.
We carried out a light and electron microscopic study on end plates and related structures in external intercostal muscles from subjects aged between 4 and 77 years. Light microscopically end plates maintained the same size, did not increase in number and showed no sprouting of terminal axons, all indicating that major compensatory histological changes to maintain adequate neuromuscular transmission with age were not required. At the ultrastructural level end plates became more complex mainly at the postsynaptic side. The latter included increased length and branching of the postsynaptic membrane with enlargement of the postsynaptic area, and degeneration of junctional folds. However, some neuromuscular junctions (NMJs) showed little branching of the postsynaptic membrane, even in old age. At the presynaptic side nerve terminals with an irregular shape were noted in the aged. Schwann cell processes were seen to intrude into the primary synaptic cleft. From these data we suggest that degeneration of the postsynaptic membrane with consequent focal denervation of NMJs is a primary event in the age-related changes of end plates. The muscle fibres showed a minor degree of type grouping in old age doubtless due to loss of motor neurons with age.
我们对4至77岁受试者的肋间外肌终板及相关结构进行了光镜和电镜研究。光镜下，终板大小保持不变，数量未增加，也未显示出终末轴突发芽，所有这些表明，随着年龄增长，无需进行主要的代偿性组织学改变来维持足够的神经肌肉传递。在超微结构水平上，终板主要在突触后一侧变得更加复杂。后者包括突触后膜长度增加和分支增多，突触后面积增大，以及连接褶退化。然而，即使在老年，一些神经肌肉接头（NMJ）的突触后膜分支也很少。在突触前一侧，老年组可见形状不规则的神经末梢。可见施万细胞突起侵入初级突触间隙。根据这些数据，我们认为突触后膜退化以及随之而来的神经肌肉接头局灶性失神经支配是终板年龄相关变化的主要事件。老年时肌纤维出现轻度的类型分组，这无疑是由于运动神经元随年龄丧失所致。
