Davidowitz J, Philips G, Breinin G M
Tissue Cell. 1980;12(3):449-57. doi: 10.1016/0040-8166(80)90035-x.
Mitochondrial volume fraction was compared among three regions along the length of six multiply innervated fibers (MIFs) in the orbital surface layer of rabbit superior rectus. These MIFs are of about 5 micrometer diameter toward the middle of their length, and of about 15 micrometer diameter toward their proximal and distal ends. The region of highest volume fraction (26%) was located toward the proximal end of their segment of minimal diameter, in apparent association with endplate-like nerve junctions. The region of lowest volume fraction (8%) was located at their distal segment of maximal diameter. The region toward the distal end of their segment of minimal diameter displayed an intermediate volume fraction (15%). These mitochondrial volume fractions were further analyzed in terms of the relative contributions of the I-band, the A-band, and the subsarcolemmal mitochondrial clusters. Comparable changes in mitochondrial content occur in both the I-band and A-band; in the fibers' distal segment of maximal diameter, however, the mitochondrial volume fraction in the A-band (5%) is lower than in the I-band (11%). These modifications of mitochondrial content along the fibers' length occur irrespective of the contributions of the subsarcolemmal mitochondrial clusters.
比较了兔上直肌眶表层六条多神经支配纤维（MIFs）全长三个区域的线粒体体积分数。这些MIFs在其长度中部直径约为5微米，在近端和远端直径约为15微米。体积分数最高的区域（26%）位于其最小直径段的近端，明显与终板样神经连接处相关。体积分数最低的区域（8%）位于其最大直径的远端段。其最小直径段远端的区域显示出中等体积分数（15%）。根据I带、A带和肌膜下线粒体簇的相对贡献，对这些线粒体体积分数进行了进一步分析。I带和A带的线粒体含量都有类似变化；然而，在纤维最大直径的远端段，A带的线粒体体积分数（5%）低于I带（11%）。这些线粒体含量沿纤维长度的变化与肌膜下线粒体簇的贡献无关。
