The study of retinal structure in frugivorous bat (Rousettus aegyptiacus) by Light and Electron microscope

Abstract

Vision is fundamentally important sense in animals for perceiving their environment, but in bat less well known. Due to the importance of vision in the bat as the only mammal that is able to fly, in present study, the retinal tissue of the frugivore bat (Rousettus aegyptiacus) was examined by light and electron microscope. So 5 male bats weighing of 123±0.8g were anesthetized, dissected, and their retina was removed. The sections (1×1mm) were isolated, fixed in 4% glutaradehyde and 2% paraformaldehyde (1hour) and rinsed with sodium cacodylate buffer (0.1). They were post fixed in osmium tetroxid 1%. The semithin sections (0.5μm) were stained with Toluidine blue, and the ultrathin sections (70 nm) were prepared. The retinal cells and layer thickness were measured by Grids-sterolite software. Obtained data were analyzed by ANOVA and t test (p < 0.05). Findings showed that the ratio of the eye’s diameter to the body length was 1:18.83. Retina layers conform to the general mammalian blueprint, but in wavy pattern with 106.61±16.19μm thickness. Inner nuclear layer was the thickest layer (18.52±1.55). Retina is duplex with dominant rod cells especially in centralis [≈25cell/(100μ)2], Cone/ Rod ratios: 1/ 7.95, and four other cell types with different density and distribution were seen. According to obtained electro-micrographs, retinal epithelial layer was thin with poor pigmentation and its surface was covered by microvilli. The arrangement of the photoreceptor parallel to the numerous choroidal papillae, and density of rod cells is higher than cone cells according to obtained results, this species of bat can be active in both dim light and daylight.