Dearden L C, Bonucci E
Calcif Tissue Res. 1975 Sep 5;18(3):173-94. doi: 10.1007/BF02546239.
As chondrocytes degenerate mitochondria frequently become vacuolated. Vacuoles seem to form by an invagination of mitochondria into their own matrix followed by cytoplasmic invasion. The bounding membrane of vacuoles and the electron dense granules which are intermittently dispersed around its periphery are positive when stained with phosphotungstic acid and with silver nitrate methenamine after periodic acid oxidation, indicating the presence of glycoprotein; they are also positive after staining with colloidal iron and bismuth nitrate, indicating the presence of acid proteoglycans. Within vacuoles and apparently arising from their glycoprotein proteoglycan boundary are small filaments composed of granular and filamentous protions. Vacuoles and their contents are exocytosed thus accounting for the presence of granules and filaments in pericellular lacunae. In pericellular lacunae and in the extracellular matrix, filaments interconnect with granules or with collagen fibrils, or both. Filaments decrease in number as the distance from the cell increases, while granules decrease in size but remain numerous. Filaments and granules decrease in the extracellular matrix as collagen fibrils aggregate and as the matric calcifies. Thus, they may play a role in aggregation of collagen fibrils. Filaments and granules also decrease with increasing age. Filaments and granules do not seem to be derived from Golgi vacuoles. They are present in costal, tracheal, and epiphyseal cartilage in three different species of animals.
随着软骨细胞退化，线粒体常常会出现空泡化。空泡似乎是由线粒体向自身基质内陷，随后细胞质侵入而形成的。空泡的边界膜以及间歇性地分散在其周边的电子致密颗粒，在用磷钨酸染色以及高碘酸氧化后用硝酸银亚甲胺染色时呈阳性，表明存在糖蛋白；在用胶体铁和硝酸铋染色后也呈阳性，表明存在酸性蛋白聚糖。在空泡内且显然源自其糖蛋白蛋白聚糖边界的是由颗粒状和丝状部分组成的小细丝。空泡及其内容物会被胞吐，这就解释了细胞周腔隙中颗粒和细丝的存在。在细胞周腔隙和细胞外基质中，细丝与颗粒或胶原纤维相互连接，或者与两者都相互连接。随着与细胞距离的增加，细丝数量减少，而颗粒尺寸减小但数量仍然众多。随着胶原纤维聚集以及基质钙化，细丝和颗粒在细胞外基质中减少。因此，它们可能在胶原纤维的聚集中起作用。细丝和颗粒也会随着年龄增长而减少。细丝和颗粒似乎并非源自高尔基体空泡。它们存在于三种不同动物的肋软骨、气管软骨和骨骺软骨中。
