Buckley I K, Raju T R
J Microsc. 1976 Jul;107(2):129-49. doi: 10.1111/j.1365-2818.1976.tb02431.x.
Attempting to throw light on the mechanical basis of movement of non-muscle (cf. muscle) cells, the present work aims to determine the form and distribution of actin and myosin in chick embryo fibroblasts. These cells were cultured on formvar, fixed in glutaraldehyde then osmium tetroxide vapours, dehydrated, critical-point dried and examined, in toto, in the electron microscope (EM). Stereoscopic pairs of micrographs were studied to define more exactly the form and distribution of cytoplasmic filaments topographically associated with deformations of the cell surface and with organelle movements through the cytoplasm. Permeating the cytoplasm, interconnecting long and short filaments closely surrounded all organelles, linked with microtubules and polyribosomes and joined to the plasma membrane. These filaments, which varied greatly in width (2-13 nm) were closely associated with large numbers of 'comma-shaped' globoid bodies of approximately 15 nm diameter. Attempting to establish the identity, form and distribution of cytoplasmic myosin, cultured cells were extracted with a cold (4 degrees C) glycerol/pyrophosphate solution for 24 h before being fixed and critical-point dried. EM examination of these cells revealed a residual three-dimensional network of branching and anastomosing 4-13 nm diameter smooth filaments, devoid of fine (2 nm) filaments and globoid bodies. Examination of fixed, critical-point dried, skeletal muscle heavy meromyosin showed globoid structures similar in form and size to the globoid bodies found in cultures fibroblasts. Similarly fixed and critical-point dried paracrystals of actin, polymerized in the presence of Mg2+, appeared as branching interconnecting filaments which, in form and dimensions, resembled the network filaments observed in pyrophosphate-extracted cells. It is concluded that the pyrophosphate-extractable globoid bodies found in cultured fibroblasts represent monomers of myosin, that the broader filaments to which these attach represent actin in Mg2+ paracrystalline form and that the various subcellular movements are brought about by interactions between the two, analogous to those occurring in muscle cells.
为了阐明非肌肉（与肌肉相对）细胞运动的力学基础，本研究旨在确定鸡胚成纤维细胞中肌动蛋白和肌球蛋白的形态及分布。这些细胞培养在福尔马林中，先用戊二醛固定，再用四氧化锇蒸汽处理，脱水，临界点干燥，然后在电子显微镜下整体观察。研究立体显微镜照片对，以更准确地确定与细胞表面变形及细胞器在细胞质中移动在地形学上相关的细胞质细丝的形态和分布。这些细丝贯穿细胞质，长短细丝相互连接，紧密围绕着所有细胞器，与微管和多核糖体相连，并与质膜相连。这些细丝宽度差异很大（2 - 13纳米），与大量直径约15纳米的“逗号形”球状小体紧密相关。为了确定细胞质肌球蛋白的特性、形态和分布，培养细胞在固定和临界点干燥前，先用冷（4摄氏度）甘油/焦磷酸溶液提取24小时。对这些细胞的电子显微镜检查显示，残留有一个三维网络，由直径4 - 13纳米的分支和吻合的光滑细丝组成，没有细（2纳米）细丝和球状小体。对固定、临界点干燥的骨骼肌重酶解肌球蛋白的检查显示，其球状结构在形态和大小上与培养的成纤维细胞中发现的球状小体相似。同样固定和临界点干燥的、在Mg2+存在下聚合的肌动蛋白副晶体，呈现为分支相互连接的细丝，其形态和尺寸类似于在焦磷酸提取细胞中观察到的网络细丝。得出的结论是，培养的成纤维细胞中焦磷酸可提取的球状小体代表肌球蛋白单体，与之相连的较粗细丝代表Mg2+副晶形式的肌动蛋白，并且各种亚细胞运动是由两者之间的相互作用引起的，类似于肌肉细胞中发生的相互作用。
