Transversal sections from the middle part of the testis were fixed in Bouin’s solution for histological examination. The spermatogenetic stage of each fish was determined according to a classification adapted from Billard and Escaf-fre : Stage I) immature stage with only A spermatogonia; Stage II) beginning of spermatogenesis with spermatogonia A and B; Stage III) spermatogonia A and В and spermatocytes; Stages IV-V) midspermatogenesis with spermatogonia to spermatozoa; Stage VI) absence of В spermatogonia; Stage VII) end of spermatogenesis with mainly spermatozoa; Stage VIII) spermiation, i.e., release of gametes (spermatozoa, and a few spermatogonia) During the experimental period, 100% of the males went through their first spermatogenetic cycle. buy diabetes drugs
Recombinant rainbow trout GH (rtGH) and recombinant tilapia GH (rtiGH; ) were generously provided by Dr. J. Smal (Eurogentec, Liege, Belgium) and Dr. F. Rentier-Delrue, respectively. The mammalian hormone preparations were pituitary-extracted bovine GH (bGH; batch bGH-B-1; NIDDK, NIH, Bethesda, MD) and pituitary-extracted ovine prolactin (oPRL; batch oPRL-19; NIDDK, NIH); bovine insulin (b-insulin) was from Sigma Chemical Company (St. Louis, MO). Trout gonadotropins (tGtHl and tGtH2; ) and salmon PRL (sPRL; ) were purified in our laboratory.