title: Rhabdom breakdown in the eye of Cirolana borealis (Crustacea) caused by exposure to daylight.
abstract: The effect of daylight on the compound eye was investigated in the deep-water crustacean isopod Cirolana borealis Lilljeborg. The animals were captured and fixed at night ('dark-exposed', i.e. not exposed to light) and day ('daylight-exposed'), respectively. Changes in light and darkness have an effect on the retinula cells; the ultrastructure of dark-exposed eyes is characterized by well-preserved organelles and cytoplasm. The photoreceptor membranes covering the microvilli are regularly aligned, and the outline of the villi is smooth. Electron-dense pigment granules are evenly distributed in the cytoplasm of the retinula cell outside the rhabdom. Daylight-exposed eyes differ from the dark-exposed eyes in the following aspects: (i) the microvilli are disrupted, (ii) retinula-cell pigment is found in the rhabdom, and (iii) the cytoplasm of retinula cells is vesiculated. These results are interpreted as retinal damage caused by excess exposure to light.
mesh_terms: D000818:Animals; D002467:Cell Nucleus / Q000648:ultrastructure; D003445:Crustacea / Q000648:ultrastructure*; D003594:Cytoplasmic Granules / Q000648:ultrastructure; D008027:Light; D008854:Microscopy, Electron; D008871:Microvilli / Q000648:ultrastructure; D009940:Organoids / Q000648:ultrastructure; D010786:Photoreceptor Cells / Q000528:radiation effects / Q000648:ultrastructure*; D010860:Pigments, Biological
chemical_list: D010860:Pigments, Biological