The sheep corpus luteum secretes inhibin

An experiment was performed in 20 Merino ewes in which ovarian venous blood was collected by venepuncture at surgery and at two stages of the oestrous cycle. The ovarian venous concentrations of inhibin, oestradiol-17 beta and progesterone were determined. The results demonstrate that during the luteal phase of the oestrous cycle the ovarian venous blood draining an ovary containing luteal tissue contains significantly more inhibin bioactivity than ovarian venous blood from an ovary not containing luteal tissue. During the follicular phase the concentration of inhibin bioactivity in ovarian venous blood was reduced compared with the luteal phase. From this data we conclude that the sheep corpus luteum secretes inhibin bioactivity into the ovarian venous blood.