Kelley M W, Ochiai C K, Corwin J T
Department of Otolaryngology-HNS, University of Virginia School of Medicine, Charlottesville 22908.
Hear Res. 1992 Apr;59(1):108-15.
New hair cells are added to the amphibian sacculus throughout life, primarily at its outer edge. The stereociliary bundles near that edge are heterogeneous, but eventually develop the more homogeneous morphology of the overwhelming majority of mature cells near the center of the epithelium. During their development the kinocilium grows and a kinociliary bulb forms. It has been proposed that initial elongation of the kinocilium is followed by shortening, and that the bulb may form during shortening. To test those hypotheses, amphibian sacculi were examined by scanning electron microscopy and the length of the kinocilium, the width of the kinociliary bulb, and the length of the tallest stereocilia were measured for 159 hair cells. The length of the tallest stereocilia on each hair cell was used as an indicator of the relative maturity of that cell, so that changes in the structure of each cell's kinocilium could be related to that cell's stage of development. Results indicate that initial elongation of the kinocilium is followed by shortening. Kinociliary bulbs first appear and increase in volume as shortening proceeds. These findings support the hypotheses. Models are proposed to explain how the formation of the bulb could result from depolymerization of apical cytoskeletal elements, and how kinocilium growth and shortening may contribute to hair bundle reorientation in the developing ear.
在整个生命周期中，两栖动物的球囊都会添加新的毛细胞，主要是在其外缘。靠近该边缘的静纤毛束是异质的，但最终会发展出上皮中心附近绝大多数成熟细胞更均匀的形态。在它们的发育过程中，动纤毛生长并形成一个动纤毛球。有人提出，动纤毛最初伸长后会缩短，并且球可能在缩短过程中形成。为了验证这些假设，通过扫描电子显微镜检查两栖动物的球囊，并测量了159个毛细胞的动纤毛长度、动纤毛球宽度和最高静纤毛的长度。每个毛细胞上最高静纤毛的长度被用作该细胞相对成熟度的指标，以便每个细胞动纤毛结构的变化可以与其发育阶段相关联。结果表明，动纤毛最初伸长后会缩短。随着缩短过程的进行，动纤毛球首先出现并体积增大。这些发现支持了这些假设。提出了模型来解释球的形成是如何由顶端细胞骨架元件的解聚导致的，以及动纤毛的生长和缩短可能如何有助于发育中的耳朵中毛束的重新定向。
