Structural domains of the muscle‐tendon junction. 1. The internal lamina and the connecting domain
Structural domains of the muscle‐tendon junction. 1. The internal lamina and the connecting domain
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肌肉-肌腱连接处的结构域 1. 内层和连接域。
DOI：
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发表时间：
1983
期刊：
影响因子：
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通讯作者：
A. Samora
中科院分区：
文献类型：
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作者：
J. Trotter;Susan Eberhard;A. Samora
脊椎动物骨骼肌纤维内产生的力在肌-腱交界处传递到肌腱。在各种实验操作后对小鼠肌-肌腱连接处进行的超微结构分析已经证明，肌-肌腱连接处可以用四个主要域来描述（Trotter和Eberhard， 1983），本报告讨论了其中两个。每个区域由其主要成分的形状和方向以及相对于质膜的位置来定义。内层由肌动蛋白丝组成，中心间距约为12 nm，主要平行于收缩力的主矢量和质膜。这些细丝被交联成一个结构单元，可能是由与它们相关的电子致密结构形成的。内部层在形态上与外部层（层密度）通过一群细丝连接，这些细丝大致垂直于收缩力的主矢量。这些构成连接域的细丝直径约为2 - 8nm，长度至少为50nm。它们穿过三个不同的区域：内层和质膜之间的肌质；质膜适当；质膜和膜层之间的细胞外空间致密。这第三个区域通常被称为透明层。这些细丝由至少三个独立的组分串联而成，通过非共价相互作用连接在一起。这些离散结构域的存在意味着每一个都有不同的分子组成和不同的力学性能。
The force generated within skeletal muscle fibers of vertebrates is transmitted to the tendon at the muscle‐tendon junction. Ultrastructural analysis of the murine muscle‐tendon junction following a variety of experimental manipulations has produced evidence that the muscle‐tendon junction can be described in terms of four principal domains (Trotter and Eberhard, 1983), two of which are discussed in the present report. Each domain is defined by the shape and orientation of its principal components, and by its position with respect to the plasma membrane. The internal lamina is composed of actin filaments, with a center to center spacing of approximately 12 nm, oriented mainly parallel to the principal vector of contractile force, and to the plasma membrane. These filaments are cross‐linked into a structural unit, perhaps by the electron‐dense structures which are associated with them. The internal lamina is morphologically connected to the external lamina (lamina densa) by a population of fine filaments oriented approximately perpendicular to the principal vector of contractile force. These filaments which constitute the connecting domain, are approximately 2–8 nm in diameter and are at least 50 nm long. They pass through three separate regions: the sarcoplasm between the internal lamina and the plasma membrane; the plasma membrane proper; and the extracellular space between the plasma membrane and the lamina densa. This third region is often referred to as the lamina lucida. These filaments are composed of at least three separate components in series, linked together by noncovalent interactions. The existence of these discrete structural domains implies that each has a different molecular composition and different mechanical properties.