Goldfischer S, Coltoff-Schiller B, Schwartz E, Blumenfeld O O
J Histochem Cytochem. 1983 Mar;31(3):382-90. doi: 10.1177/31.3.6186732.
Microfibrils are the insoluble, 10- to 12-nm components of the extracellular matrix that are involved in elastogenesis. Reports of their ultrastructure vary: they have been described as tubular and beaded and as nontubular filaments that are devoid of any periodicity. Ultrastructurally, microfibrils resemble oxytalan fibers that have been observed in peridontal membranes, skin, and other locations. Whether microfibrils have the staining characteristics of oxytalan is difficult to determine in tissues because available light microscopic stains also stain elastin. Calf aortic smooth muscle cells grown in media without added ascorbate provide a unique model for examining the ultrastructure and staining characteristics of chemically defined microfibrils. Microfibrils are the predominant insoluble extracellular protein in such cultures, which do not deposit collagen or elastin. These studies demonstrate that microfibrils are tubular structures with 10- and 12-nm striations and have the same staining characteristics as oxytalan, reacting with aldehyde fuchsin and orcein after oxidation. Microfibrillar protein is enriched in glutamic and aspartic acids and the electron density of microfibrils is enhanced by fixation in the presence of cationic dyes. In such preparation, microfibrils are made visible within the core of amorphous elastin as well as in regions that are free of elastin. The widespread distribution of microfibrils (oxytalan) indicates that their function extends beyond elastogenesis. Their localization within tissues suggests that they serve as an elastic attachment protein in sites that are subject to mechanical stress.
微原纤维是参与弹性生成的细胞外基质中不溶性的10至12纳米成分。关于它们超微结构的报道各不相同：它们被描述为管状和串珠状，以及没有任何周期性的非管状细丝。在超微结构上，微原纤维类似于在牙周膜、皮肤和其他部位观察到的耐酸纤维。在组织中很难确定微原纤维是否具有耐酸纤维的染色特征，因为现有的光学显微镜染色剂也会对弹性蛋白染色。在不添加抗坏血酸的培养基中培养的小牛主动脉平滑肌细胞为研究化学定义的微原纤维的超微结构和染色特征提供了一个独特的模型。微原纤维是此类培养物中主要的不溶性细胞外蛋白，这些培养物不会沉积胶原蛋白或弹性蛋白。这些研究表明，微原纤维是具有10纳米和12纳米条纹的管状结构，并且具有与耐酸纤维相同的染色特征，氧化后与醛复红和地衣红反应。微原纤维蛋白富含谷氨酸和天冬氨酸，并且在阳离子染料存在下固定可增强微原纤维的电子密度。在这种制备中，微原纤维在无定形弹性蛋白的核心以及没有弹性蛋白的区域中都可见。微原纤维（耐酸纤维）的广泛分布表明它们的功能超出了弹性生成。它们在组织内的定位表明它们在承受机械应力的部位充当弹性附着蛋白。
