EFFECTS OF FETAL BOVINE SERUM, FSH AND 17-BETA-ESTRADIOL ON THE CULTURE OF BOVINE PREANTRAL FOLLICLES

We describe a 7-d culture in droplets of collagen gel of isolated smal l bovine preantral follicles in medium with or without 10% fetal bovin e serum (FBS). In addition, the effect of human recombinant FSH and 17 beta-estradiol on the morphology and growth of the preantral follicle s was investigated in medium without FBS. After culture in medium with 10% FBS, the increase in follicle diameter was 13.1+/-8.4 mu m, the p ercentage of BrdU-labeled cells was 49.9+/-11.3 and the number of cell s per area granulosa was 11.1+/-1.8. Omission of serum from the cultur e medium had no effect on the percentage of labeled cells, but the dia meter increase was lower and the cells were smaller. Apparently, serum affects the size of the granulosa cells from small preantral follicle s rather than the stimulation of cell proliferation. Addition of human recombinant FSH and/or 17 beta-estradiol to serum-free medium resulte d in a larger diameter increase during culture compared with that of t he control. With FSH, this was due to an increase in cell proliferatio n, while with estradiol this was caused by an increase in granulosa ce ll size. The effects of simultaneous treatment with FSH and estradiol was simply the combination of their individual effects. In conclusion, small bovine preantral follicles can be cultured for 7 d in the absen ce of serum and hormones. The follicles increase in diameter and react to FSH with enhanced cell proliferation and to estradiol with an incr ease in cell size.