FSH AND GROWTH FACTORS AFFECT THE GROWTH AND ENDOCRINE FUNCTION IN VITRO OF GRANULOSA CELLS OF BOVINE PREANTRAL FOLLICLES

摘要

The hypothesis was tested that bovine preantral follicles can be stimulated to grow in vitro by FSH and by the mitogens, epidermal growth factor (EGF) and basic fibroblast growth factor (bFGF), but not by transforming growth factor-beta (TGF beta), which generally inhibits EGF and bFGF action. Preantral follicles, 60 to 179 mu m in diameter, were isolated from fetal ovaries by treatment with collagenase and DNase and cultured for 6 d in serum-free medium, with or without FSH and growth factors. Basic FGF (50 ng/ml), and to a lesser extent FSH (100 ng/ml) and EGF (50 ng/ml), stimulated thymidine incorporation by granulosa cells in bovine preantral follicles compared to control cultures (8-, 4- and 2.5-fold the labeling index of the controls; P<0.05). Alone TGF beta (10 ng/ml) had no effect on H-3-thymidine incorporation, but it completely inhibited the bFGF- but not the FSH-stimulated increase in the labeling index and mean follicular diameter of preantral follicles (P<0.05). By the end of the culture period oocytes in most treatments had degenerated, and the few surviving oocytes were in preantral follicles cultured with FSH or bFGF. Progesterone accumulation was greater (P<0.05) in the presence of FSH (100 ng/ml) or EGF (50 ng/ml) than with bFGF, TGF beta or control medium. Basic FGF strongly inhibited the effect of FSH on progesterone secretion (P<0.05). Only FSH stimulated the conversion of exogenous testosterone to estradiol and both bFGF and TGF beta markedly inhibited FSH-stimulated estradiol accumulation. These results indicate that proliferation of granulosa cells of bovine preantral follicles can be stimulated by bFGF, FSH and EGF, whereas TGF beta inhibits growth, and that they are steroidogenically active in culture. Basic FGF and TGF beta antagonize FSH-stimulated steroid production by granulosa cells of cultured bovine preantral follicles.