Tsuprun V, Santi P
Department of Otolaryngology, University of Minnesota, Minneapolis 55455, USA.
J Neurocytol. 1998;27(7):517-28. doi: 10.1023/a:1006903926571.
The structure of side, tip, and "attachment" links of chinchilla outer hair cell (OHC) stereocilia was studied by transmission and scanning electron microscopy using tannic acid and Cuprolinic blue histochemical procedures. Tannic acid, which interacts with many different types of proteins and glycoproteins irrespective of their electrical charge, showed strong reactivity for the central area of the side links and weak reactivity for the marginal area of these links adjacent to the stereocilia membrane. Tannic acid treatment revealed the tip links as thin strands, about 5 nm thick. Attachment links were poorly visualized after tannic acid treatment and appeared as sparse filamentous strands at tips of the tallest OHC stereocilia. Cuprolinic blue, at a high critical electrolyte concentration, reacted with strongly negative, primarily sulfated, carbohydrate residues of glycoconjugate macromolecules. In contrast to the tannic acid treatment, the central portions of the OHC stereocilia side links were unstained after Cuprolinic blue treatment; however, membrane-associated ends of these links were darkly stained. The tip links showed a similar appearance as after tannic acid treatment; however, Cuprolinic blue revealed an electron-dense substructure at both ends of its insertion into the stereocilia. Cuprolinic blue reactive structures were also observed as attachment links only at the tips of the OHC stereocilia of the tallest row in each bundle. These structures formed a crown-like array around the tip of each stereocilium. Their primary function appears to be attachment of type B fibrils of the tectorial membrane to the tallest OHC stereocilia. Cuprolinic blue reactive structures of the side, tip, and attachment links appear to contain acidic, sulfated residues of proteoglycans or glycoproteins. These structures may function as connective elements between the stereocilia links and the hair cell cytoskeleton.
采用单宁酸和铜叶绿酸蓝组织化学方法，通过透射电子显微镜和扫描电子显微镜研究了毛丝鼠外毛细胞（OHC）静纤毛的侧面、顶端及“附着”连接结构。单宁酸能与许多不同类型的蛋白质和糖蛋白相互作用，而不论其电荷如何，它对侧面连接的中心区域显示出强反应性，而对这些连接靠近静纤毛膜的边缘区域反应性较弱。单宁酸处理显示顶端连接为细链，约5纳米厚。单宁酸处理后，附着连接难以清晰显示，在最高的OHC静纤毛顶端呈现为稀疏的丝状链。在高临界电解质浓度下，铜叶绿酸蓝与糖缀合物大分子中强负性、主要为硫酸化的碳水化合物残基发生反应。与单宁酸处理不同，铜叶绿酸蓝处理后OHC静纤毛侧面连接的中心部分未被染色；然而，这些连接与膜相关的末端被深染。顶端连接呈现出与单宁酸处理后相似的外观；然而，铜叶绿酸蓝显示其插入静纤毛的两端有电子致密的亚结构。仅在每束中最高排的OHC静纤毛顶端观察到铜叶绿酸蓝反应性结构作为附着连接。这些结构在每个静纤毛顶端周围形成冠状排列。它们的主要功能似乎是将盖膜的B型纤维附着到最高的OHC静纤毛上。侧面、顶端及附着连接的铜叶绿酸蓝反应性结构似乎含有蛋白聚糖或糖蛋白的酸性硫酸化残基。这些结构可能作为静纤毛连接与毛细胞细胞骨架之间的连接元件发挥作用。
