MITOCHONDRIAL SIZE AND SHAPE IN EQUINE SKELETAL-MUSCLE - A 3-DIMENSIONAL RECONSTRUCTION STUDY
MITOCHONDRIAL SIZE AND SHAPE IN EQUINE SKELETAL-MUSCLE - A 3-DIMENSIONAL RECONSTRUCTION STUDY
复制标题
DOI：
10.1002/ar.1092220405
复制
发表时间：
1988-12-01
影响因子：
--
通讯作者：
WEIBEL, ER
中科院分区：
文献类型：
--
作者：
KAYAR, SR;HOPPELER, H;WEIBEL, ER
单个线粒体是由马半腱肌中选定的肌纤维的超薄连续切片重建的，长度接近两个肌节。人们发现线粒体具有高度可变性，单个线粒体的大小和复杂性随着线粒体占据的纤维的分数而增加。在线粒体体积密度小于 4% 的纤维中，对应于快肌糖酵解纤维的线粒体含量，线粒体通常呈相当简单的圆柱形，方向与肌原纤维平行。在线粒体体积密度超过7%的纤维中，对应于慢氧化或快速氧化糖酵解纤维的线粒体含量，线粒体在肌肉肌节的A带和Z板水平通常呈圆柱形。然而，这些线粒体通常具有发生在 I 带水平的横向延伸或互连。单个线粒体的体积范围从千分之几μ3到最大线粒体的不完全重建部分的几个μ3。人们发现，从单个部分分类为肌膜下的线粒体剖面与纤维内更深的其他剖面相互连接。这表明肌膜下线粒体和原纤维间线粒体不太可能是两个结构不同的群体。然而，我们没有发现任何证据表明网状结构将肌纤维中的所有线粒体物质完全互连。
Individual mitochondria were reconstructed from ultrathin serial sections of selected muscle fibers in the M. semitendinosus of a horse, over a length of nearly two sarcomeres. Mitochondria were found to be highly variable, with size and complexity of single mitochondria increasing with the fractional part of a fiber occupied by mitochondria. In fibers with a mitochondrial volume density of less than 4%, corresponding to the mitochondrial content of fast-twitch glycolytic fibers, mitochondria were generally rather simple cylindrical shapes, oriented parallel to the myofibrils. In fibers with a mitochondrial volume density of more than 7%, corresponding to the mitochondrial content of slow-oxidative or fast-oxidative glycolytic fibers, mitochondria were generally cylindrical at the A-band and Z-plate level of the muscle sarcomeres. However, these mitochondria often had transverse extensions or interconnections that occurred at the I-band level. Volumes of individual mitochondria ranged from as small as a few thousandths of a .mu.3 up to several .mu.3 for the incompletely reconstructed portions of the largest mitochondria. Mitochondrial profiles that one would classify from single sections as subsarcolemmal were found to interconnect with other profiles deeper with other profiles deeper witin the fiber. This suggests that it is unlikely that subsarcolemmal and interfibrillar mitochondria are two structurally distinct populations. However, we found no evidence of a reticulum completely interlinking all mitochondrial material in a muscle fiber.