This Study Concerns the morphological changes of the testes of "curimbatá", Prochilodus scrofa (Steindachner, 1881) at the beginning of sperm production, before and after the hormonal injections. We examined 25 three year old males that were reared in tanks at the Experimental Fish and Frog Culturing Station of Pindamonhangaba of the Fisheries Institute of São Paulo. The testes were sampled at the start of sperm production, after the first hormone injection (5 IU/g for weight of hCG), and 14 days before and after a second injection. Testicle fragments of these specimens were fixed and embedded in historesin. At the beginning of sperm production, the milky-white gonad showed consistem superficial vascularization, exceeding thick sperm under light pressure. Microscopically, the presence of spermatogonia, many spermatocytes, spemiatids and some tubules with spermatozoa were conspicuous. After the first hormonal dose, the gonads increased in volume, occupying most of the abdominal cavity superficial blood irrigation was evident, and sperm flowed easily out of the genital pore. Many spermatozoa were observed in the histology sections, along with spermatocytes and spemiatids, within the lumen of the seminal tubules. After 14 days, the testes exhibited decreased volume and pink-white coloration. Light microscopy revealed few spermatozoa and disarrangement of the structures forming the seminal tubules. After the second hCG dose, the testes again increased in volume, occupying most of the abdominal cavity. Some tubules were filled with spermatozoa whereas others showed reduced numbers of this cellular type.
Prochilodus scrofa; fish; testes; morphology; hormonal stimulation