中华绒螯蟹光感受器超微结构在昼夜光周期中的变化

ULTRASTRUCTURE CHANGES OF THE PHOTORECEPTOR IN THE CRAB,ERIOCHEIR SINENSIS BY DIURNAL PHOTOPERRIODISM

用透射电镜对中华绒螯蟹光感受器的超微结构进行了研究。光感受器的基本组成单位———小眼，从远侧端到近侧端是由角膜、４个晶锥细胞形成的晶锥、一个在前端的小网膜细胞和７个纺锤形的小网膜细胞聚合而成的小网膜以及周围的多种色素细胞构成。这些结构与已知的甲壳动物的光感受器相似。在小网膜细胞中多囊体、板膜体、溶酶体等细胞器主要集中在细胞核与核下的层面中。通过对黎明（０５∶１５）、正午（１２∶００）、黄昏（１７∶００）和夜晚（２２∶００）４个时间取的材料的研究，发现小网膜细胞的超微结构随昼夜光照周期发生节律性的变化。特别以感光部位———感杆束的面积和结构的变化最为明显。另外在小网膜细胞中内质网、线粒体、板膜体和胞饮泡等细胞器的形态和数量也随光周期呈现出规律性的变化。同时各种色素颗粒和脂滴的分布位置也随光照的改变而发生移动。

Electron microscopic observation revealed that the photoreceptor of crab (Eriocheir sinensis) is composed of cornea, four cone cells, eight retinular cells, with one located in distal part and the other seven spindle cells form a retinula, and pigment cells. Many organelles of retinular cell, such as multivesicular bodies, vesicular lamellar bodies and lamellar bodies, concentrate in the distal region around the nucleus. The preparations fixed separately at dawn (05∶15), at noon (12∶00), at dusk (17∶00) and in night (22∶00), were studied. The results show that fine structure of the retinular cell changed with day night rhythum. The variations of the dimensions of rhabdom and microvillus fine structure were especially obvious. The morphology and number of granular endoplasmic reticulum, mitochondria, multivesicular bodies, lamellar bodies and pinocytotic vesicles in the retinula changed with the day night rhythum. At the same time the location of the pigment granules and lipid droplets were affected too.