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Joaquin De Juan, Bassima Boughlala, Noemi Martinez-Ruiz, Biotechnology Alicante University; Spinules of cone horizontal cells in European sea bass are more numerous in the dorsal and nasal peripheral retina. Are spinules biological detectors to peripheral vision of teleosts?. Invest. Ophthalmol. Vis. Sci. 2013;54(15):6087.
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© ARVO (1962-2015); The Authors (2016-present)
Teleost is a successful vertebrate group, constituting more than 50% of vertebrate species. These fishes are the only vertebrate group that presents spinules from the lateral dendrites of Cone Horizontal Cells into cone pedicles. Previously, we observed that the number of spinules in any given species depended on both taxonomic placing and degree of predatory behavior. Then, species with the most spinules were also the most predatory and vice versa. The aim of this work was to study the density of spinules and synaptic ribbons, per cone pedicle, in central and peripheral retina.
The study was performed on European sea bass (Dicentrarchus labrax), one specie of teleost fish belonging to perciform order and moronidae family. Light-adapted fishes were sacrificed. Retinas were extracted and whole mounts embedded in EPON for transmission-electron-microscopy study. Thin sections from eight representative retinal areas were observed and photographed in an Electron Microscope. The number of spinules and synaptic ribbons, per cone pedicle, were counted. Finally, univariate and multivariate statistics (p<0.05) were applied to compare the results.
The number of spinule per pedicle was a 25% greater (≈19 spinules/pedicle) in the peripheral retina than in the central one (≈14 spinules/pedicle). These values were higher in peripheral nasal retina (≈22 spinules/pedicle) and the peripheral dorsal one (≈21 spinules/pedicle), regarding to values in remaining areas (≈15 spinules/pedicle). However, the number of synaptic ribbons per pedicle do not show significant differences between peripheral and central retina, neither between the eight remaining areas studied.
1) The spinules are more abundant in the retinal periphery that in the central area. The density is higher in the periphery of the nasal and dorsal quadrants regarding the remaining retinal areas. These areas detect the visual information from lateral and inferior visual field. 2) The synaptic ribbons density is the same through all retina. 3) The adult European sea bass is a predator and piscivore (eating fishes) teleost. The predatory behaviours in perciformes use the chasing and to attain high cruising and accelerating speeds, may use the highest spinule density in peripheral areas of the retina to act as prey detectors.
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