Gale J E, Meyers J R, Corwin J T
Department of Otolaryngology-HNS, University of Virginia School of Medicine, Charlottesville 22908, USA.
J Assoc Res Otolaryngol. 2000 Sep;1(2):172-82. doi: 10.1007/s101620010037.
The frog inner ear contains eight sensory organs that provide sensitivities to auditory, vestibular, and ground-borne vibrational stimuli. The saccule in bullfrogs is responsible for detecting ground- and airborne vibrations and is used for studies of hair cell physiology, development, and regeneration. Based on hair bundle morphology, a number of hair cell types have been defined in this organ. Using immunocytochemistry, vital labeling, and electron microscopy, we have characterized a new hair cell type in the bullfrog saccule. A monoclonal antibody that is specific to hair cells revealed that a population of solitary hair cells exists outside the sensory macula in what was previously thought to be nonsensory epithelium. We call these extramacular hair cells. There are 80-100 extramacular hair cells in both tadpole and adult saccules, which extend up to 1 mm from the edge of the sensory macula. The extramacular hair cells have spherical cell bodies and small apical surfaces. Even in adults, the hair bundles of the extramacular cells appear immature, with a long kinocilium (6-9 microm) and short stereocilia (0.5-2 microm). At least 90% of extramacular hair cells are likely to be innervated as demonstrated by labeling of nerve fibers with an antineurofilament antibody. The extramacular hair cells may differentiate in regionsjust beyond the edge of the macula at an early stage in development and then be pushed out via the interstitial growth of the epithelium that surrounds the macula. It is also possible that they may be produced from cell divisions in the extramacular epithelium that has not been considered capable of giving rise to hair cells.
蛙的内耳包含八个感觉器官，这些器官对听觉、前庭和地面传播的振动刺激具有敏感性。牛蛙的球囊负责检测地面和空气传播的振动，并用于毛细胞生理学、发育和再生的研究。基于毛束形态，在这个器官中已经定义了多种毛细胞类型。通过免疫细胞化学、活体标记和电子显微镜，我们已经鉴定出牛蛙球囊中一种新的毛细胞类型。一种对毛细胞特异的单克隆抗体显示，在以前被认为是非感觉上皮的感觉斑之外存在一群孤立的毛细胞。我们将这些细胞称为斑外毛细胞。蝌蚪和成年球囊中都有80 - 100个斑外毛细胞，它们从感觉斑边缘向上延伸达1毫米。斑外毛细胞具有球形的细胞体和小的顶端表面。即使在成年个体中，斑外细胞的毛束看起来也不成熟，有一根长的动纤毛（6 - 9微米）和短的静纤毛（0.5 - 2微米）。用抗神经丝抗体标记神经纤维表明，至少90%的斑外毛细胞可能接受神经支配。斑外毛细胞可能在发育早期在感觉斑边缘之外的区域分化，然后通过围绕感觉斑的上皮的间质生长被推出。它们也有可能由以前被认为不能产生毛细胞的斑外上皮中的细胞分裂产生。
