Membrane structure of Golgi apparatus, chloroplasts and mitochondria observed by freeze-substitution

采用冷冻代入法研究了尖刺田鼠（Scenedesmus acuminatus）高尔基体、叶绿体和线粒体的膜结构。这些膜大部分明显呈现三层结构。通过从剩余的电子致密膜蛋白中分离脂质组分，可以看到这三层结构。远端高尔基池的上膜和下膜在池中心紧密接触。在类囊体中也观察到两种膜的类似接触。转移囊泡、分泌囊泡和池缘的电子密度非常高。这些发现与传统化学固定的结果有很大的不同，表明冷冻取代在保存结构而不变形和防止成分物质溶解方面优于化学固定。

The membrane structure of Golgi apparatus, chloroplasts and mitochondria in Scenedesmus acuminatus was studied by the freeze-substitution method. Most of these membranes clearly exhibited three-layered structures. It was interpreted that the three layers were visualized by resolving the lipid component from membranes remaining electron dense membrane proteins. The upper and lower membranes of the distal Golgi cisternae were in close contact with each other at the cisternal centre. Similar contact of two membranes was also observed in thylakoids. The electron density of transfer vesicles, secretory vesicles, and cisternal margins was very high. These findings differ considerably from those obtained by conventional chemical fixation, and suggest that freeze-substitution is superior to chemical fixation for preserving structures without distortion and preventing dissolution of constituent substances.