CORNER CONE TOPOGRAPHY IN THE RETINA OF THE ATLANTIC SALMON: SPATIO-TEMPORAL DIFFERENCES WITH CORNER CONE DISTRIBUTIONS IN THE RETINA OF RAINBOW TROUT
The distribution of corner (ultraviolet-sensitive) cones in the retina of Atlantic salmon was examined from the small juvenile (parr) stage to the adult stage (approaching sexual maturation). Small parr weighing ~ 5 g lacked corner cones everywhere except near the dorsal periphery. Large fish ( ~ 5...
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| Format: | Text |
| Language: | English |
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.533.3377 http://www-heb.pac.dfo-mpo.gc.ca/congress/2002/Growth/novales.pdf |
| Summary: | The distribution of corner (ultraviolet-sensitive) cones in the retina of Atlantic salmon was examined from the small juvenile (parr) stage to the adult stage (approaching sexual maturation). Small parr weighing ~ 5 g lacked corner cones everywhere except near the dorsal periphery. Large fish ( ~ 5 Kg) approaching sexual maturation showed corner cones in other areas of the dorsal retina besides the periphery. These areas had similar corner cone densities to analogous areas in the smolt retina, suggesting that corner cones are formed in the periphery and re-incorporated into the dorsal retina of the Atlantic salmon some time during the smolt stage. This incorporation is partial both in numbers of cones and in location (only the dorsal retina is affected). These findings contrast with the situation in rainbow trout where corner cones from existing mosaics are only partially lost from the ventral retina, if at all, and where production and incorporation of these cones into the dorsal retina occurs throughout life. Thus, in salmonids, there are at least two different ontogenetic pathways that determine retinal corner cone distributions. |
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