Structure of the stereocilia side links and morphology of auditory hair bundle in relation to noise exposure in the chinchilla
Structure of the stereocilia side links and morphology of auditory hair bundle in relation to noise exposure in the chinchilla
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DOI：
10.1023/b:neur.0000021906.08847.d2
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发表时间：
2003-11
期刊：
影响因子：
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通讯作者：
V. Tsuprun;P. Schachern;Sebahattin Cureoglu;M. Paparella
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文献类型：
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作者：
V. Tsuprun;P. Schachern;Sebahattin Cureoglu;M. Paparella
静纤毛侧链直接参与毛细胞中静纤毛束完整性的维持。用透射电镜观察了灰鼠静纤毛侧链结构和听毛束形态与噪声暴露的关系。外毛细胞（OHC）静纤毛侧链由细胞外、近膜和细丝状区组成。两条珠状细丝在其远端折叠，并在静纤毛之间的中心固定成一个小球。细胞内的膜下层似乎在肌动蛋白核心和侧链的细胞外近膜区域之间形成了一座桥梁。在正常生理条件下，大多数OHC静纤毛有规则的侧链分布，静纤毛轴之间形成“拉链状”网格。内毛细胞（IHC）静纤毛的侧链具有类似的丝状外观，但与OHC静纤毛相比，观察到的不太常见，并且结构组织减少。OHC和IHC静纤毛的超微结构分析表明，大量的侧链可以存活114 dB SPL 2小时或123 dB SPL 15分钟的声刺激，导致所有动物的暂时性听阈升高。对于连接不良或缺乏侧链的IHC静纤毛和OHC静纤毛，更常见静纤毛的混乱、分离、紧密附着和融合。大多数紊乱的OHC和IHC静纤毛在14-28天后恢复到正常直立状态，侧链方向恢复，这与听觉敏感性的几乎完全恢复相关。然而，即使在28天后，在一些静纤毛上也观察到质膜直接附着、断裂连接、融合和水泡，并且似乎是永久性的。
Stereocilia side links are directly involved in the maintenance of stereociliary bundle integrity in hair cells. The structure of the stereocilia side links and morphology of the auditory hair bundle in relation to noise exposure in the chinchilla was investigated by transmission electron microscopy. The outer hair cell (OHC) stereocilia side link was suggested to consist of extracellular, juxta-membrane and thin filamentous regions. Two beaded filaments were folded at their distal ends and fastened in one globule in the center between stereocilia. An intracellular, submembraneous layer appeared to form a bridge between the actin core and the extracellular, juxta-membrane region of the side link. In normal physiological conditions, most OHC stereocilia had a regular distribution of side links, forming a ‘zipper-like’ lattice between stereocilium shafts. Side links of the inner hair cell (IHC) stereocilia had a similar filamentous appearance, but were observed less commonly and had decreased structural organization compared to those of the OHC stereocilia. Ultrastructural analysis of OHC and IHC stereocilia showed that a large number of the side links could survive acoustic stimulation of 114 dB SPL for 2 hrs or 123 dB SPL for 15 min, that resulted in temporarily elevated hearing thresholds in all animals. Disarray, separation, close attachment and fusion of stereocilia were more frequently observed for IHC stereocilia and OHC stereocilia that were poorly connected or that lacked side links. Most disarrayed OHC and IHC stereocilia recovered to a normal erect state with restored orientation of the side links after 14–28 days, which correlated with near-complete recovery of auditory sensitivity. However, direct attachment of plasma membranes, ruptured links, fusion and blebs were seen on some stereocilia even after 28 days and appear to be permanent.