Spangenberg D B, Coccaro E, Schwarte R, Lowe B
Department of Pathology, Eastern Virginia Medical School, Norfolk 23507, USA.
Scanning Microsc. 1996;10(3):875-87; discussion 887-8.
Ultrastructural studies of the statocysts and touch-plates of graviceptors (rhopalia) of Aurelia ephyrae revealed that (1) touch-plate hair cells are present; and (2) cytoplasmic strands from the hair cell bases extend from the neurite plexus to touch similar strands from the lithocytes. This close association of hair cell neurites and statocysts may have important implications regarding the transmitting and processing of positional information with respect to the gravity vector. Graviceptors of ephyrae which developed while weightless in microgravity were compared with controls at the ultrastructural level. We found that hair cells of ephyrae which developed in microgravity had fewer lipid droplets in the large spaces near their bases as compared with 1 g controls. In the ephyrae from the first microgravity experiment, hair cells had more large apical vacuoles with filamentous content than were found in hair cells of ephyrae from the second experiment and controls. The neurite plexus and the network of cytoplasmic strands extending to the statocysts were not different in microgravity-developed ephyrae from controls. Behavioral differences in swimming and orienting in ephyrae in microgravity and controls (reported earlier) were not explained by morphological differences in the hair cells of the touch-plates or the statocysts, although functional differences apparently occurred.
对海月水母碟状体的平衡囊和重力感受器（触手囊）进行的超微结构研究表明：（1）存在触板毛细胞；（2）毛细胞基部的细胞质丝从神经纤维丛延伸出来，与来自石细胞的类似丝状物相接触。毛细胞神经突与平衡囊的这种紧密联系可能对重力矢量位置信息的传递和处理具有重要意义。将在微重力环境下失重发育的碟状体重力感受器与对照组进行超微结构层面的比较。我们发现，与1g对照组相比，在微重力环境下发育的碟状体毛细胞基部附近的大空间中脂滴较少。在首次微重力实验的碟状体中，毛细胞的顶端大液泡中含有丝状物质，比第二次实验和对照组的碟状体毛细胞中的更多。在微重力环境下发育的碟状体中，神经纤维丛和延伸至平衡囊的细胞质丝网络与对照组并无差异。微重力环境下和对照组的碟状体在游泳和定向方面的行为差异（先前已有报道），无法通过触板或平衡囊毛细胞的形态差异来解释，尽管功能差异显然存在。
