Activin Stimulates Follicle Formation and Activation and Modulates Steroidogenesis in Fetal Bovine Ovarian Tissue in Vitro 1

The earliest stages of ovarian follicular development, follicle formation and development the capacity to activate, are critical size reserve. In primates most domestic animals, these occur during fetal life thus, difficult study. Our laboratory has used cattle, an excellent model for human elucidate regulation early in bovine tissue vitro. experiments described here were designed determine if ovaries have activin A its receptors affects and/or activation begin growth. During second trimester, when follicles first form, increased total number primary (activated) cultured cortical pieces, compared control medium; effects similar positive control, insulin. decreased primordial numbers secondary follicles, again mimicking control. previous showed that produce steroids, particularly estradiol progesterone inhibit activation. gonadotropin-treated progesterone, but androstenedione accumulation medium. Messenger RNA type II was detected ovaries, with ACVR2A receptor mRNA more abundant than ACVR2B. Immunohistochemistry localized germ cells all stages, granulosa cells, theca follicles. Staining ACVR2B weaker mostly confined calls. Taken together, results strongly suggest origin 3 plays a role by promoting modulating steroidogenesis.