Kaneko H, Okamoto M, Goshima K
Exp Cell Res. 1984 Aug;153(2):483-98. doi: 10.1016/0014-4827(84)90615-3.
Newt embryonic myocardial cells can undergo mitosis in culture. The successive changes in the striation pattern of sarcomeres of myofibrils during mitosis were studied by polarization microscopy without fixing or killing the cells. Birefringence of well-organized striation patterns, i.e., bright A-bands and dark I-bands, was clearly visible in interphase cells and did not show any detectable changes during incubation for 3 h or more. Electron microscopy showed the presence of well-organized myofibrils with Z-bands in these interphase cells. When myocardial cells entered the mitotic stage, the birefringence of striation pattern of their myofibrils gradually changed with the pattern in small parts of the myofibrils gradually becoming indistinct (called 'indistinct striation' in this paper). These indistinct regions increased in size during the mitotic stage. In addition, in some regions of the indistinct striation, the birefringence of sarcomeres gradually decreased and finally disappeared (called 'disappearance of sarcomeres' in this paper). No myocardial cells underwent mitosis without these disruptive changes of the myofibril striation patterns. In the post-mitotic stage, the well-organized striation of the myofibrils reappeared. Electron microscopy showed disorganized sarcomeres without Z-bands in the regions of indistinct striation, and no well-organized myofibrils in the regions where the sarcomeres had disappeared. Thus the well-organized myofibrils with Z-bands became transiently disorganized at least in some parts, during mitosis. They were then reorganized into daughter myocardial cells.
蝾螈胚胎心肌细胞在培养中可进行有丝分裂。通过偏振显微镜研究了有丝分裂期间肌原纤维肌节条纹模式的连续变化，且未对细胞进行固定或杀死处理。在间期细胞中，组织良好的条纹模式（即明亮的A带和黑暗的I带）的双折射清晰可见，并且在孵育3小时或更长时间内未显示任何可检测到的变化。电子显微镜显示这些间期细胞中存在带有Z带的组织良好的肌原纤维。当心肌细胞进入有丝分裂阶段时，其肌原纤维条纹模式的双折射逐渐变化，肌原纤维小部分的模式逐渐变得模糊（本文中称为“模糊条纹”）。这些模糊区域在有丝分裂阶段尺寸增大。此外，在模糊条纹的某些区域，肌节的双折射逐渐降低并最终消失（本文中称为 “肌节消失”）。没有心肌细胞在肌原纤维条纹模式没有这些破坏变化的情况下进行有丝分裂。在有丝分裂后阶段，肌原纤维组织良好的条纹重新出现。电子显微镜显示在模糊条纹区域的肌节无序且没有Z带，在肌节消失的区域没有组织良好的肌原纤维。因此，带有Z带的组织良好的肌原纤维在有丝分裂期间至少在某些部分暂时变得无序。然后它们重新组织成子代心肌细胞。
