Kano Y, Fujimaki N, Ishikawa H
Department of Anatomy, Gunma University School of Medicine, Japan.
Cell Struct Funct. 1991 Jun;16(3):251-61. doi: 10.1247/csf.16.251.
The distribution and arrangement of microtubules (MTs) in skeletal muscle fibers of the rat and mouse diaphragm were examined by thin-section electron microscopy. In the central portion of muscle fibers, most MTs ran longitudinally between myofibrils and beneath the sarcolemma, and some MTs ran transversely predominantly at the level of the I band, especially of the A-I junction, thus forming a lattice-like arrangement. At the fiber periphery, MTs were aggregated in the perinuclear region, from which they radiated to take a longitudinal course beneath the sarcolemma and to run in a transverse direction at the I-band level. In the end portion of muscle fibers, MTs were abundant and ran longitudinally into sarcoplasmic processes. MTs were often found to be spatially associated with membranous organelles. Quantitative analyses indicated that the longitudinally running MTs were remarkably more numerous in the peripheral zone of muscle fibers than in the deeper zones. The density of MTs in the central portion was almost the same in both red and white muscle fibers. The density was significantly higher at the fiber ends, though it varied considerably among different fibers. These results are discussed with special reference to the possible involvement of MTs in intracellular transport as well as structural support.
通过超薄切片电子显微镜检查了大鼠和小鼠膈肌骨骼肌纤维中微管（MTs）的分布和排列。在肌纤维的中央部分，大多数微管在肌原纤维之间和肌膜下方纵向排列，一些微管主要在I带水平，尤其是A-I交界处横向排列，从而形成晶格状排列。在纤维周边，微管聚集在核周区域，从该区域它们放射状延伸，在肌膜下方呈纵向排列，并在I带水平横向延伸。在肌纤维的末端部分，微管丰富并纵向延伸到肌浆突中。微管经常在空间上与膜性细胞器相关联。定量分析表明，纵向排列的微管在肌纤维周边区域比在较深区域明显更多。红色和白色肌纤维中央部分微管的密度几乎相同。尽管不同纤维之间差异很大，但纤维末端的密度明显更高。结合微管在细胞内运输以及结构支撑方面可能的作用，对这些结果进行了讨论。
