Proceedings: Regulation of steroid secretion in sheep ovarian follicles

The Effect of HCG or Endogenous Gonadotrophin on Normal Bovine Follicular Activity

“…There was a significant decline (P<0-02, by Student's t test) in oestradiol-17ß concentration by the 12th hour Effect of HCG or LH on bovine follicular activity after administration of either dose of HCG in nine experiments, the exception being one cow which did not respond by a decrease in oestradiol-17ß or by production of a functional CL. The present study in the cow in vivo confirms work in vitro in which LH caused a precipitous drop in oestrogen secretion by cultured sheep follicles (McIntosh & Moor, 1973). After HCG injection in the six successful experiments, there was no significant increase in endogenous LH concentration before ovulation.…”

Inhibition of Cholesterol Biosynthesis in Ovine Ovarian Follicles in vitro by Human Chorionic Gonadotrophin

“…The medium with additions was sterilized by Millipore filtration. This concentration of hCG was considered as appropriate because it has been demonstrated to transform the ovine ovarian follicle from an eostrogen to a progesterone producer in culture (McIntosh and Moor 1973). Incubation was carried out at 37°C in the presence of a special gas mixture (5 % CO 2 , 50 % O2 , 45 % N 2 ) .…”

“…Luteinizing hormone (LH) has ·clearly been shown to stimulate progesterone biosynthesis in vitro by ovarian tissues of several species (Savard et ale 1965 ;Armstrong 1968; McIntosh and Moor 1973;Younglai 1977). The stimulatory effect of LH on steroidogenesis appears to be primarily located at post-cholesterol sites in the pathway, at least in rat lutein tissue (Major et ale 1967; Solod et ale 1967), rabbit ovarian tissue (Armstrong 1967), and bovine luteal tissue (Armstrong et ale 1970).…”