@entity7928 salamanders have been used in visual science because of the large size of their cells and the ease of preparation and maintenance of in vitro retinal preparations. We have found that salamanders over 27 cm in length show a variety of @entity227 . Compared to smaller animals (15-23 cm), large animals exhibited a decrease in visual responses determined by tests of the optomotor reflex. Small animals responded correctly an average of 84.5% of the time in visual testing at three light levels compared to an average of 68.4% for the large animals with the poorest visual performance at the lowest level of illumination. In addition, large animals contained (i) histological degeneration of the outer retina, in particular, loss and disruption of outer segments and abnormalities of the retinal pigmented epithelium, (ii) loss of cells, including photoreceptors, by apoptosis as evaluated with the TUNEL technique, and (iii) an increase in the number of macrophages and lymphocytes within the retina as determined by morphological examination. These histological changes were present in all large animals and all quadrants of their retinas. In contrast, small animals showed virtually no @entity2000 , no TUNEL-positive cells, and few immune-like cells in the retina. Since large animals are also older animals. the visual changes are age-related. @entity227 in the outer retina also typify aged @entity1 eyes. Thus, we propose that large salamanders serve as an animal model for age-related @entity2000 . In addition to providing a source of aging retina that is readily accessible to experimental manipulation, the salamander provides a pigmented retina with a mixed (2:1, rod:cone) population of photoreceptors, similar to the degeneration-prone parafoveal region of the @entity1 eye.

Age-related changes in the XXXX salamander retina.

@entity1 :: ('9606', 'Species') :: ['human'] @entity2000 :: ('MESH:D012162', 'Disease') :: ['retinal degeneration'] @entity227 :: ('MESH:D014786', 'Disease') :: ['visual abnormalities', 'Loss of visual function and histological degeneration'] @entity7928 :: ('9694', 'Species') :: ['Tiger']
@entity7928 :: (9694,Species) :: ['tiger']
