Primary cilia mediate sensory signaling in multiple organisms and cell types but have structures adapted for specific roles. Structural defects in them lead to devastating diseases known as ciliopathies in humans. Key to their functions are structures at their base: the basal body, the transition zone, the "Y-shaped links," and the "ciliary necklace." We have used cryo-electron tomography with subtomogram averaging and conventional transmission electron microscopy to elucidate the structures associated with the basal region of the "connecting cilia" of rod outer segments in mouse retina. The longitudinal variations in microtubule (MT) structures and the lumenal scaffold complexes connecting them have been determined, as well as membrane-associated transition zone structures: Y-shaped links connecting MT to the membrane, and ciliary beads connected to them that protrude from the cell surface and form a necklace-like structure. These results represent a clearer structural scaffold onto which molecules identified by genetics, proteomics, and superresolution fluorescence can be placed in our emerging model of photoreceptor sensory cilia.

中文翻译：

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通过冷冻电子断层扫描揭示感光器纤毛的中心粒和过渡区结构。

初级纤毛在多种生物体和细胞类型中介导感觉信号传导，但具有适应特定作用的结构。它们的结构缺陷会导致人类罹患毁灭性疾病，称为纤毛病。它们功能的关键在于其基部的结构：基体、过渡区、“Y 形链接”和“纤毛项链”。我们使用冷冻电子断层扫描与亚断层平均和传统透射电子显微镜来阐明与小鼠视网膜杆外节的“连接纤毛”基底区域相关的结构。微管（MT）结构和连接它们的管腔支架复合体的纵向变化已经确定，以及膜相关的过渡区结构：将 MT 连接到膜的 Y 形链接，以及连接到它们的从微管突出的纤毛珠。细胞表面形成项链状结构。这些结果代表了一个更清晰的结构支架，通过遗传学、蛋白质组学和超分辨率荧光鉴定的分子可以放置在我们新兴的光感受器感觉纤毛模型中。