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NC de Oliveira Miguel, CA Elias, S Allodi; UVB and UVC Rays Effects on the Visual System of the Crab Ucides Cordatus and Wistar Rats . Invest. Ophthalmol. Vis. Sci. 2002;43(13):4529.
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Purpose: The visual system and the skin are the interfaces between the environment and the living organisms, so these organs can be used as experimental targets to study possible alterations of animals submitted to radiations. The crab retina and lamina ganglionaris, and the rat retina are then useful structures to make such a study, besides allowing a correlation between the visual system of invertebrates and vertebrates. The conventional preparation of specimens for transmission electron microscopy (TEM) observation is adequate to detect these modifications quite accurately. In this study we have analysed by TEM how the retinas of both species and the lamina ganglionaris cells of the crab answered to 30 minutes exposure to ultraviolet B (UVB) and ultraviolet C (UVC) radiation (DOSE: 0.38 Watts/m2 and 0.4 Watts/m2, respectively). Methods: Male adult crabs with carapace ranging between 5.7 and 8.0 cm and male adult Wistar rats weighing between 210 and 270 g were used in the experiments. Both experimental models were exposed to a mercury lamp, which emitted mainly UVB and UVC rays. The crabs were anesthetized by chilling before the optic stalks were dissected and the rats were anesthetized with pentobarbital before perfusion through the heart with a fixative solution (paraformaldehyde and glutaraldehyde in 0.1M phosphate buffer, pH 7.4). After dissection small fragments of both visual systems were immersed in the same fixative in 0.1M cacodylate buffer (pH 7.4) for 2h. The material was then dehydrated, embedded in Polybed 812® and sectioned in an ultramicrotome. Ultrathin sections were observed under the electron microscope. Results: The results show that in the crabs, the damage occurred in the retina and lamina ganglionaris cells . Morphologic alterations of the pigment granules and an increase in the quantity of lipid droplets were observed in the cells. Alterations include an increase in heterocromatin, karyolyses, karyorrhexis, distention of the rough endoplasmic reticulum and mithochondria disruption. In the rat retina, cells in the inner plexiform and ganglion cell layers were the ones that displayed most changes. The rat retina showed alterations similar to the ones related in the crabs besides presenting more myelin figures. Conclusion: These morphological modifications indicate an apoptotic process and also that the wavelengths tested (254nm, 312nm) are dangerous to the visual system both in vertebrates and invertebrates. Support: CNPq, FAPERJ, FUJB-UFRJ
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