Comparative studies on the histology of eye retina in some Nile fishes with different dial activities

Aim of the work: the present work aimed to study the comparative histology of some fresh water fishes inhabiting the Nile River in Egypt. These fishes have different dial activities; Oreochromis niloticus is diurnal,while Clarias gariepinus, Bagrus bajad and Chrysichthys auratus are nocturnal

Results: the retinae of all studied fishes [O. niloticus,C. gariepinus, B. bajad and Ch. auratus] are composed of ten layers. These layers are the inner limiting membrane [ILM], nerve fiber layer [NFL], ganglion cell layer [GCL], inner plexiform layer [IPL], inner nuclear layer [INL], outer plexiform layer [OPL], outer nuclear layer [ONL], outer limiting membrane [OLM], photoreceptor layer [PL] and pigmented epithelial layer [PE]. The histological structure showed three types of the photoreceptors [single and double cones as well as single rods] in Oreochromis niloticus. The pigment epithelium layer in C. gariepinus, B.bajad and Ch. auratus completely hides the photoreceptors. A considerable variation was recorded between the different studied fishes in the whole retinal thickness as well as their retinal layers

Conclusion: whole retinal thickness in O. niloticus [diurnal activity] is large in comparison with that of the other three siluriform fishes [nocturnal activity]

Histopathological studies on some vital organs of mice exposed to extremely low frequency magnetic field

Twenty five male Swiss albino mice were used in this study to detect the effect of extremely low frequency magnetic field [ELFMF] 2 milli Tesla-50 Hertz [2 mT,50 Hz] 8 hours/day at different time intervals. Mice were divided into five groups, control group and 4 treated groups, two groups represented the direct effect of [ELFMF] and the other two represented the late effect. The direct effect groups were sacrificed direcly after the end of exposure to [ELFMF], while the late effect groups were sacrificed after certain duration period of the exposure away from [ELFMF]. In the present work, histopathological studies revealed severe degeneration changes in kidney, spleen and testes of all groups of mice direct and late effect groups and no sign of complete recovery could be detected in the late effect groups. Glomerular volume, number of glomeruli, relative glomerular blood volume [RGBV] of the kidney; and the mean number cells of spermatogenesis cells of the testes were calculated in control and treated groups. The histopathological changes observed in the kidney, spleen and testes of treated mice were less in direct effect groups than that observed in late effect groups