Indoleamine-accumulating cells and dopaminergic cells are distributed similarly in carp retina

Carp (Cyprinus carpio) retinas were processed for simultaneous visualization of dopaminergic (DA) and indoleamine-accumulating (ID) cells in flat-mounts under fluorescence microscope. A mixture of 5 micrograms noradrenaline (NA) and 5 micrograms 5,6-dihydroxytryptamine (5,6-DHT) was injected intravitreally into the eyes 2 h before enucleation. The spatial distribution and density were compared between NA-loaded DA-cells (greenish fluorescence) and 5,6-DHT-loaded ID-cells (yellowish). The two classes of cells were found to distribute similarly in a mixed fashion. Their densities were higher in the peripheral region than in the rest and extremely high at the retinal margin. Where the densities were higher, the size of cell bodies tended to be smaller. DA-cells were generally larger than ID-cells. Those cells, located in the intermediate and peripheral regions, appeared to be arranged in radial rows originating at the optic disc.