Reproductive cycle of Salmo irideus Gibbons (Pisces, Salmoniformes) in intensive culture: macrocospic and microscopic characterization of the testis

Abstract

Five adults male specimens of Salmo irideus Gibbons were collected every month, during eleven months for micro and macroscopic identification of their cyclic gonadal modulation. The gonads were macroscopically characterized by their colour, volume and superficial vascularization. For microscopic analysis, testis were excised in their medial and caudal portion and fixed in Bouin's fluid. The results showed that the reproductive cycle of the male of Salmo irideus can be classified as follows: maturing (early and latter), ripenning and spent. Macroscopically, in early maturing, gonads are filiform, pink with delicate blood vessels; in latter maturing, testis are white, exhibiting a great increase of volume, and in ripenning, gonads are wide and longer than the abdominal cavity, presenting a spontaneous sperm flow. At the spent phase gonads are small, flacid and pink-reddish. Microscopical analysis showed that in early maturing there is a predominance of cysts containing primary and secondary spermatocytes besides spermatides and sperm cells; in latter maturing the predominance is of spermatids and of secondary spermatocytes, presenting also a great amount of sperm cells in the lobule lumen; in ripenning, a predominance of sperm cells in the lobule occurs; in the spent, only residual sperm cells are found. Spermatogonia are observed throughout all stages of gonadal development.