CHANGES IN THE DISTRIBUTION OF FIBROBLAST GROWTH-FACTOR IN THE TELEOSTEAN TESTIS DURING SPERMATOGENESIS

The distribution of fibroblast growth factor (FGF) in the testes of Sa lvelinus and Oryzias latipes was investigated by immunofluorescence st aining. In S. leucomaenis, spermatogonia were strongly stained in the infantile testis. When human chorionic gonadotrophin (HCG) was injecte d into individual fish, the uptake of 5-bromo 2'-deoxyuridine (BrdU) o ccurred within a day. At the same time, FGF became undetectable in spe rmatogonia, but appeared for the first time around the testicular soma tic cells. A similar distribution was seen in the mature testes of S. leucomaenis and O. latipes. The positively immunostained area correspo nded to the predominant site of the Sertoli cells. This pattern of dis tribution of FGF suggests that FGF plays an important role in the init iation and progression of spermatogenesis in the teleostean testis. (C ) 1995 Wiley-Liss, Inc.