English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

Vision is a complex process in teleost fishes inhabiting different habitats, especially those exhibiting both nocturnal and diurnal behaviors. In the present study, four species of freshwater teleosts were collected from the River Nile at Dakahlia Governorate, Egypt. These include three nocturnal species, Clarias gariepinus (Clariidae), Malapterurus electricus (Malapteruridae) and Anguilla anguilla (Anguillidae), and one diurnal fish Oreochromis niloticus (Cichlidae). The ocular regions of the selected teleosts were dissected and their lens, cornea and retina were processed for histological, morphometric, scanning and transmission electron microscopy investigations. Morphologically, the gross structure of the ocular region varied between the species. The lens exhibited organized lens fibers with characteristic ball and socket structure densely grouped in Clarias gariepinus and Oreochromis niloticus compared to less compacted fibers in Anguilla anguilla, becoming widened at both peripheral lens angles in Malapterurus electricus. The cornea was pigmented in Anguilla anguilla and clear in the other examined fishes. The retinal thickness and visual acuity were markedly increased in the nocturnal fishes compared to the diurnal species. Also, the photoreceptors of the nocturnal fishes were composed mainly of rods and few single and double cones. The neural circuit of retinal cells showed comparatively increased distribution of amacrine and Müller cells in between the ganglion and inner nuclear cells in both C. gariepinus and M. electricus. These data suggest that nocturnal fishes C. gariepinus, M. electricus and A. anguilla and the diurnal fish O. niloticus exhibited differences in their corneal, lenticular and retinal structures, accommodated to their diurnal and nocturnal behaviors.

folia biologica

Comparative Structural and Functional Study on the Eye of Freshwater Teleosts: Clarias gariepinus, Malapterurus electricus, Anguilla anguilla and Oreochromis niloticus