Ovulation in the perfused rabbit ovary: the influence of prostaglandins and prostaglandin inhibitors

Ovulation has been achieved in vitro in the isolated perfused rabbit ovary. The ovarian artery was cannulated 8 h after HCG administration and the ovary perfused and removed for in vitro study. The effects on ovulation of the addition of PGE₂, and PGF(2α), indomethacin and HCG to the perfusate were studied. Ovulation occurred in 8 of 12 perfused ovaries in the control group (no drug), 7 of 12 in the group perfused with supplementary HCG (1 IU/ml), 11 of 12 with PGF(2α) (1 μg/ml), 3 of 12 with PGE₂ (1 μg/ml) and 2 of 12 with indomethacin (0.5 μg/ml). Ovulation always occurred in the contralateral ovary which remained in situ as an in vivo control. Addition of indomethacin to the perfusate reduced the incidence of ovulation in vitro when compared to the control group (P<0.01). Ovulation was also reduced (P<0.01) when the ovaries treated with PGE₂ were compared to the control, and when PGE₂ was compared to PGF(2α) (P<0.005). These observations indicate that the presence of PGF(2α) within the ovary may be essential to the process of ovulation. The inhibitory effects of indomethacin and PGE₂ on ovulation in the perfused in vitro rabbit ovary parallel previous observations in the intact HCG-treated rabbit. The use of the perfused preparation provides additional evidence that the inhibitory effects of indomethacin and PGE₂ on ovulation are mediated at the ovarian level. Simultaneous recordings of ovarian contractions were carried out and no association could be established between contractile δvulation or number of ovulation points.