Studies On The Ultrastructural Changes Of The Photoreceptor Of Miers (Portunus Tritubereulatus) In Different Light Adaptation

Ultrastructure of photoreceptor in Miers {portunus tritubereulatus) wasstudied under electron microscope. We observed the surface structure and inner structure of the compound eyes. And we also studied the change process of the ultrastructure of the compound eyes in different light adaptation. Comparative studies on the structure differences of photoreceptor between Portunus tritubereulatus and Metapenaeusensis were also done. It is the first time to report this experiment. Part I Comparisons of the ultrastructure of photoreceptor in Miers in light and dark adaptationThe ultrastructure of photoreceptor in Miers {portunus tritubereulatus), which was light or dark adapted and were fixed separately at dawn(05:15), at noon(12:00), at dusk(17:00) and in night(22:00), were studied by electron microscopy. The results showed that the fine structure of the photoreceptor, the diameter of rhabdom, the dimension of perirhabdom vacuole, the number of pinocytotic vesicle below the microsvilli, the location of pigment granules, the emergence of lamellar bodies and lysosomes in cytoplasm, were different in light and dark adaptation. Though the photoreceptor was in a steady adaptation, its ultrastructure of the rhabdom was smaller at noon than that in night. The changes of the ultrastructures, such as visicule and lamellar body in the cytoplasm, were large than the structures at dawn and at dusk.Part II Ultra-structure changes of the compound eyes of miers in different light adaptation.After 12 hours dark adaptation, photoreceptors of miers were stimulated with different wavelength light. We used four different wavelength light including red light(750nm),yellow light(580nm),green light(560nm),blue light(400nm) to stimulatefour different groups compound eyes. Then the ultrastructures of the compound eyes of each group were observed under electron microscope. The results showed the fine structure of the photoreceptor, the diameter of rhabdom, the dimension of perirhabdom vacuole, the number of pinocytotic vesicle below the microsvilli, the location of pigment granules, the emergence of lamellar bodies and lysosomes in cytoplasm, were different in different light adaptation. The results also showed that the diameter of rhabdom was biggest and microsvilli arranged regularly under the red light stimulation. However, the diameter of rhabdom was smallest and microsvilli arranged irregularly under blue light adaptation.Part III Comparative studies on the morphology and ultrastructure of compound eyes in two kinds of crustacean.The morphology and fine structure of compound eyes in two species(portunus tritubereulatus, metapenaeus ensis) were studied by electron microscope. The results under scanning electron microscope were that the compound eye of miers is semi-globular. The surface area of the compound eyes is about 25.12mm2.The ommatidia that form the compound eye are hexagon. On the back of the compound eye there is a thumb-shaped area where have no ommatidia. However, the compound eye of metapenaeus ensis is globular. The ommatidia that form the compound eye is rectangle. There is no thumb-shaped area on the back of the compound eye. The results under transmission electron microscope show that the fine structure of the compound eye in portunus tritubereulatus is different from that in metapenaeus ensis. The former has eleven retinular cells which composed the compound eye. The later has eight retinular cells which composed the compound eye. There are two kinds retinular cell that have different function in the Crustacea.