Growth rate of a peripheral annulus defined by neurotoxic destruction in the goldfish retina

Fifteen goldfish of similar size (6.8 cm in body length on the average) were reared in an aquarium (about 22 degrees C) for 5 months after neurotoxic destruction of retinal dopamine (DA) cells with intravitreal injection of 6-hydroxydopamine, and then further for 8 months after destruction of indoleamine-accumulating cells with 5,7-dihydroxytryptamine. By means of a histofluorescence technique for retinal wholemounts, the growth rate and the number of DA cells were estimated for a peripheral annulus which had been well defined by the successive neurotoxic destructions of monoamine-accumulating cells. As the fish grew from 8.4 to 11.6 cm in body length on the average over the 8-month period, the defined peripheral annulus of the retina was found to be enlarged radially by approximately 1.5 X and circumferentially by 1.3 X while the number of DA cells in the annulus remained unchanged.