The Effects of Progesterone and Human Chorionic Gonadotropin on Ovulation in the in Vitro Perfused Rabbit Ovary

Abstract

The in vitro perfused rabbit ovary preparation was used to study the effect of progesterone on follicle rupture and to determine the minimum level of human chorionic gonadotropin (hCG) required to induce ovulation in vitro. Both ovaries from an intact female rabbit were removed and simultaneously placed in separate perfusion systems. In four groups of five rabbits each, hCG at a dose of 25, 10, 5, or 1 IU was added to the perfusate of both ovaries. An additional group received no hCG. One ovary from each rabbit was treated with progesterone (1 mg/150 ml of perfusate) together with hCG. The contralateral ovary served as a control, receiving only hCG. The number of ovaries ovulating in each group varied directly with the amount of hCG added to the perfusate (four of five with 25 IU, three of five with 10 IU, two of five with 5 IU, one of five with 1 IU, and none of five without hCG). In each group the number of ovulations per ovary did not increase significantly by the addition of progesterone to the perfusate. These data suggest that a dose-response relationship can be established between hCG and ovulation in the in vitro model and that amounts of hCG as small as 1 IU can produce ovulation in an in vitro perfused rabbit ovary preparation. Although exogenous progesterone did not appear to influence ovulation in this model, these data do not exclude the possibility that progesterone exerts a direct facilitatory effect on ovulation.