Baird I L, Lowman G F
Anat Rec. 1978 May;191(1):69-70. doi: 10.1002/ar.1091910107.
Scanning and transmission electron microscopy have been used to investigate the structure of the papilla neglecta in the lizard, Anolis carolinensis. Situated in the posterior part of the utricle, the receptor is innervated by a branch of the posterior ampullary nerve and is covered by an extracellular membrane that exhibits a tapering extension into the orifice of the utriculo-saccular duct. The neuroepithelium contains two populations of sensory cells within a matrix of sustentacular cells; one population (non-calyceal hair cells) is supplied primarily by boutons and clublike terminals, while the other (calyceal hair cells) is served by calycine terminals that invest from one to five sensory cells. The apices of calyceal hair cells bulge into the utricular lumen and have larger diameters and ciliary counts than non-calyceal cells, but other differences are not marked. Although the bases of calyceal hair cells are deeply indented by calyceal processes, both types show similar afferent synaptic structures confined to the nuclear and infranuclear regions. Efferent terminals synapse on afferent endings and hair cells in both cases; synapses directly on calyceal hair cells lie above the calyx, just beneath the apicolateral junctional complexes. Those complexes are basically similar throughout the receptor, except that a hemispheroidal gap junction between a supporting cell and adjacent hair cell was noted in several instances. Arrays of endoplasmic reticulum and specialized mitochondria occur adjacent to aggregations of afferent synaptic vesicles in both types of sensory cell; it is suggested that such arrays may participate in the production of the vesicles in a process involving membrane recycling similar to that at the neuromuscular junction. Differences between calycine units and the type I hair cell of mammals are discussed, and evidence that suggests an equilibratory function for the lacertilian papilla neglecta is presented.
利用扫描电子显微镜和透射电子显微镜研究了绿安乐蜥（Anolis carolinensis）椭圆囊隐窝的结构。该感受器位于椭圆囊后部，由后壶腹神经的一个分支支配，被一层细胞外膜覆盖，该膜向椭圆囊 - 球囊管的开口处呈逐渐变细的延伸。神经上皮在支持细胞基质内包含两种感觉细胞群体；一种群体（非杯状毛细胞）主要由终扣和棒状终末提供神经支配，而另一种（杯状毛细胞）由杯状终末提供神经支配，杯状终末包裹一至五个感觉细胞。杯状毛细胞的顶端向椭圆囊腔突出，其直径和纤毛数量比非杯状细胞大，但其他差异并不明显。尽管杯状毛细胞的基部被杯状突起深深凹陷，但两种类型的细胞在核区和核下区都显示出相似的传入突触结构。在这两种情况下，传出终末都与传入末梢和毛细胞形成突触；直接与杯状毛细胞形成的突触位于杯状结构上方，就在顶外侧连接复合体下方。整个感受器中的这些复合体基本相似，只是在一些情况下注意到一个支持细胞与相邻毛细胞之间存在半球形缝隙连接。在两种类型的感觉细胞中，内质网和特殊线粒体的排列都出现在传入突触小泡聚集区附近；有人提出，这种排列可能在一个涉及膜再循环的过程中参与小泡的产生，类似于神经肌肉接头处的情况。讨论了杯状单元与哺乳动物I型毛细胞之间的差异，并提供了表明绿安乐蜥椭圆囊隐窝具有平衡功能的证据。
