title: Ultrastructural study of first and second order neurons in the visual system of the crab Ucides cordatus following exposure to ultraviolet radiation.
abstract: The visual system as an interface between the environment and the living organism can serve as a sensitive indicator especially in studies that deal with effects of radiation. The crab retina as the seat of the photoreceptors and the lamina ganglionaris as the place of second order neurons were the targets of our study. Conventional specimen preparation techniques for transmission electron microscopy (TEM) are adequate to preserve any modifications that may occur as a consequence of the experimental treatment. In this study we analyzed by TEM how retinal and lamina ganglionaris cells of the crab Ucides cordatus responded to a 30 min exposure to ultraviolet C (UV-C) and ultraviolet B (UV-B) radiation with doses of 7200 and 590J/cm(2), respectively. The results show that damaged cells occurred in both retina and lamina ganglionaris, but that the retinal cells were affected to a greater extent. Morphological alterations of the pigment granules and an increase in the quantity of lipid droplets of the retinal cells were also observed. Additional changes include an increase in heterochromatin, nuclear karyolyses and karyorrhexes, distention of rough endoplasmic reticulum and mitochondrial disruptions. The observed morphological changes are indicative of apoptotic processes and show that an exposure to light of wavelengths of 254 and 312 nm may be injurious to the visual system of invertebrates.
authors.affiliation: Departamento de Histologia e Embriologia, Centro de Ciências da Saude, Instituto de Ciencias Biomédicas, Universidade Federal do Rio de Janeiro, Ilha do Fundão, 21941-590 Rio de Janeiro, RJ, Brazil.
authors.forename: Nádia Campos
authors.initials: NC
authors.lastname: de Oliveira Miguel
authors.forename: Victor Benno
authors.initials: VB
authors.lastname: Meyer-Rochow
authors.forename: Silvana
authors.initials: S
authors.lastname: Allodi
mesh_terms: D000818:Animals; D003386:Brachyura / Q000502:physiology / Q000528:radiation effects*; D008297:Male; D008854:Microscopy, Electron; D009474:Neurons / Q000528:radiation effects* / Q000648:ultrastructure; D012160:Retina / Q000166:cytology / Q000528:radiation effects*; D014466:Ultraviolet Rays / Q000009:adverse effects*; D014785:Vision, Ocular / Q000528:radiation effects*