Influence of prostaglandins and human chorionic gonadotrophin on progesterone concentration and oocyte maturation in mouse ovarian follicles maintained in organ culture.

The response of mouse ovaries maintained in organ culture to prostaglandin E-2 (PGE2) and prostaglandin F-2alpha (F2alpha) was assessed using quantitative histological and radioimmunoassay procedures. Prostaglandin E2 induced histological changes in the cultured follicles comparable to those induced by human chorionic gonadotrophin (HCG) and the increase in the number of oocytes undergoing preovulatory maturation over the control value was the same irrespective of the treatment (PGE2 alone, HCG alone, or PGE2+HCG). The amount of progesterone/ml of culture medium was also significantly higher with these preparations than in control cultures (about 125 ng/ml compared with 57 ng/ml). By contrast, 5 mug PGF2alpha/ml medium increased neither the number of oocytes undergoing maturation nor the concentration of progesterone in the culture medium. The latter increased when the dose of PGF2alpha was increased to 30 mug/ml, although the proportion of oocytes beyond the dictyate stage remained at the control level. There was no augmentation in the response (above the level for HCG alone) when HCG and PGF2alpha were added to the explant medium simultaneously. These results are discussed in terms of the possible mechanism of action of the various preparations.