KNAPPEIS G G, CARLSEN F
J Cell Biol. 1962 May;13(2):323-35. doi: 10.1083/jcb.13.2.323.
This electron microscopic study deals with the structure of the Z disc of frog's skeletal muscle, with special regard to the I filaments-whether they pass through the Z disc or terminate at it. In most longitudinal sections the I filaments terminate as rod-like projections on either side of the Z disc, one I filament on one side lying between two I filaments on the opposite side. This indicates that the I filaments are not continuous through the Z disc. The rod-like projections are often seen to consist of filaments (denoted as Z filaments) which meet at an angle. In cross-sections through the Z region the I filaments and Z filaments form tetragonal patterns. The I filaments are situated in the corners of the squares; the oblique Z filaments form the sides of squares. The tetragonal pattern formed by the Z filaments is rotated 45 degrees with respect to the tetragons formed by the I filaments on both sides of Z. This structural arrangement is interpreted to indicate that each I filament on one side of the Z disc faces the center of the space between four I filaments on the opposite side of Z and that the interconnection is formed by four Z filaments.
这项电子显微镜研究探讨了青蛙骨骼肌Z盘的结构，特别关注I带细丝——它们是穿过Z盘还是终止于Z盘。在大多数纵向切片中，I带细丝在Z盘两侧以杆状突起的形式终止，一侧的一根I带细丝位于另一侧的两根I带细丝之间。这表明I带细丝并非连续穿过Z盘。这些杆状突起通常由以一定角度相交的细丝（称为Z细丝）组成。在通过Z区域的横切面中，I带细丝和Z细丝形成四边形图案。I带细丝位于正方形的角上；倾斜的Z细丝构成正方形的边。由Z细丝形成的四边形图案相对于Z两侧由I带细丝形成的四边形旋转了45度。这种结构排列被解释为表明Z盘一侧的每根I带细丝面对Z盘另一侧四根I带细丝之间空间的中心，并且这种连接是由四根Z细丝形成的。
