线粒体（mitochondrion）是一种存在于大多数真核细胞中的由两层膜包被的细胞器，直径在0.5到10微米左右。大多数真核细胞都拥有线粒体。线粒体是细胞内氧化磷酸化和合成三磷酸腺苷（ATP）的主要场所，除了为细胞供能外，线粒体还参与诸如细胞分化、细胞信息传递和细胞凋亡等过程，并拥有调控细胞生长和细胞周期的能力。
Mitochondria from kidney tubule of mouse, showing the double-membraned envelope (E), lamellar cristae (C), matrix (M) and dense granules (circle). At the base of a crista (arrow) continuity between the inner membrane of the mitochondrion and the membranes of the crista can be discerned. In some zones (*) the cristae are presumably tangentially cut and hence not visualized in the electron micrograph. X 90000
图为小鼠肾小管的线粒体，显示双膜包被（E）、片状嵴（C）、基质（M）和致密颗粒（圈）。在嵴的底部（箭头）可以看出线粒体内膜和嵴的膜之间的连续性。在一些区域（*），嵴状体可能被切开，因此在电子显微照片中无法看到。X 90000
一般来说，一个组织的代谢活动与线粒体的数量和大小以及嵴的数量、大小、表面积和浓度之间相互影响。这一点可以通过比较下图1&2印证。相对而言，大多数骨骼肌和平滑肌的例子都有较少的线粒体和较少的嵴膜。线粒体分布方向与微管一致，通常分布在细胞功能旺盛的区域。
Fig. 1. Liver of a winter-starved frog, showing abundant glycogen deposits (G) and mitochondria (M) with sparse cristae. X 24 000
Fig. 2. Dragon-fly flight muscle, showing voluminous mitochondria (M) with abundant complex cristae. Note also the close association between the smooth endoplasmic reticulum (arrow) and the mitochondria (page 226). X 34 000
图1. 冬季青蛙的肝脏，显示丰富的糖原沉积（G）和线粒体（M）与稀疏的嵴。X 24 000
图2. 蜻蜓飞行肌，显示大量的线粒体（M）和丰富的复合嵴。注意光滑的内质网（箭头）和线粒体之间的联系。X 34 000
From human acute leukaemic cells.
Fig. 1 A partially transformed mitochondrion presenting a ring-shaped profile. X 74000 Fig.
2 and 3. These illustrations probably depict the sequential stages of membranous whorl formation from mitochondria showing ring-shaped profiles. X 58000; X 66000
来自人类急性白血病细胞。
图1. 一个部分转化的线粒体呈现环状轮廓。X 74000
图2和3。从线粒体呈现环形轮廓的膜轮形成的顺序阶段。X 58000；X 66000
Normal rat myocardium showing mitochondria with concentric cristae.X 41 000
正常大鼠心肌显示有同心嵴的线粒体。X 41 000
Fig. 1.Mitochondria with longitudinally orientated cristae from a kidney tubule of a winter-starved frog.X 56000
图1.来自冬季饥饿的青蛙肾小管的线粒体具有纵向定向的嵴。X 56000
Fig. 2.Human acute leukaemic cell.Three mitochondria with longitudinally arranged cristae are seen.One shows complete transformation (C), the other two partial transformation(P).X 45000
图2人类急性白血病细胞。 三个线粒体上有纵向排列的嵴的线粒体。 一个显示 完全转化（C），其他两个部分转化 (P). X 45000
Fig. 3.Human acute leukaemic cell, showing partially transformed mitochondria,one of which shows a C-shaped profile,x 41 000
图3人类急性白血病细胞，显示部分转化的线粒体。 其中一个显示C形的轮廓。 x 41 000
Fig. 1. Cross section of a mitochondrion showing dot array of filaments and triangular profiles of transversely cut prismatic cristae. X 152000
图1. 线粒体的横截面，显示点状排列的细丝和横向切割的棱形嵴的三角形轮廓。X 152000
Fig. 2. Mitochondrion showing dot array of filaments and rhomboidal profiles of transversely cut prismatic cristae. X 100000
图2. 线粒体显示点状排列的细丝和横向切割的棱形嵴的斜方体轮廓。X 100000
来源于：Ultrastructural Pathology of the Cell and Matrix