| Budget Amount *help |
¥1,800,000 (Direct Cost: ¥1,800,000)
Fiscal Year 1989: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1988: ¥1,300,000 (Direct Cost: ¥1,300,000)
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| Research Abstract |
In this experiment, the nymphal and adult compound eyes of dragonflies (Anax nigrofasciatus) were comparatively studied. A compound eye of the nymph is divided into two parts, X and Y-region. X-region occupies a small dorsal part in the nymphal compound eye and is a presumptive area of a dorsal part of an adult compound eye, whereas Y-region is a functional part of a nymphal compound eye occupying a major part of a compound eye. In the present studies, the nymphal compound eyes of the last nymphal stage were used.
Morphological studies revealed that a length of an ommatidial retinula of X-region is as short as a quarter of retinula in Y-region, and it has a very tiny rhabdomal microvilli at the center of retinula with a small density of intramembrane particles on their freeze-fractured P-face. Biochemical studies with HPLC showed that x-region contains retinal as chromophore of visual substance with very small amount just detectable by HPLC, whereas Y-region contains two kinds of chromophores, 3-hydroxyretinal and retinal with a ratio of 3:1. This uneven distribution of chromophore species in a nymphal compound eye has remained in the dorsal and ventrat parts of an adult compound eye.
By electrophysiological experiments, the relations between response amplitudes and the intensities of stimulus white light were recorded, and it is found that retinular cells in X-region can respond to light stimulus with a very low sensitivity about 1/1,000 of retinular cell of Y-region.
From the results mentioned above, it can be concluded that there are close and parallel relations among the surface area of rhabdomal microvilli, chromophore contents and the electrical responses during the development of compound eyes.
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