EFFECT OF FIBROBLAST GROWTH FACTOR-II ON SERTOLI CELLS AND GONOCYTES IN COCULTURE DURING THE PERINATAL-PERIOD

Sertoli cell-gonocyte cocultures obtained from rat testes 20 days post coitum, 1 day postpartum, and 3 days postpartum were used to investiga te the effect of FGF-2 on both somatic and germ cells tn vitro during the perinatal period. With cells isolated from fetal, newborn, or 3-da y-old animals, FGF-2 was found to significantly increase the number of Sertoli cells after 3 or 6 days of cultures, starting at a concentrat ion of 1 ng/ml. FGF-2 did not increase the [H-3]thymidine labeling ind ex of Sertoli cells, indicating that FGF-2 is a survival factor for th ese cells in vitro. FGF-2 (1, 5, or 10 ng/ml) also significantly incre ased the number of gonocytes after 6 days of culture with cells from e ither newborn or 3-day-old animals. About twice as many germ cells wer e found in those cultures compared to the control cultures. Addition o f a neutralizing antibody against FGF-2 to control cultures caused a s ignificant decrease in the number of gonocytes compared to that in unt reated cultures after 6 days, whereas with FGF-2, the antibody decreas ed the number of germ cells to control levels. FGF-2 significantly sti mulated the proliferative activity of the gonocytes after 3 or 5 days, indicating that FGF-2 is a survival as well as a mitogenic factor for these cells. Taken together, these data suggest that FGF-2 is an impo rtant factor around the start of spermatogenesis, at least in vitro.