Fertilizability of unovulated mature eggs following indomethacin administration in mice.

Using mice as subjects, we investigated the effects of indomethacin (ID) on follicle rupture and nuclear maturation, and studied the fertilizability of ova retained in the follicles as a result of ovulation inhibition by ID. Ten units each of PMSG and hCG were administered intraperitoneally to mice at 56-hr intervals to induce superovulation. ID was administered 90 min after hCG injection. The ova recovered from the oviduct 17 hr after hCG injection numbered 32.2 +/- 7.8, 16.9 +/- 5.8, 5.6 +/- 2.9, and 1.0 +/- 1.3 for mice receiving 0, 0.5, 1.0, and 2.0 mg ID, respectively, demonstrating dose-dependent inhibition of ovulation. Ten hours after hCG administration, the intrafollicular ova that had matured to metaphase second stage comprised 43% in both groups. The fertilization rate (73.7%, 56/76) for the follicle-retained eggs in the 2 mg ID mice was similar to that for controls (72.9%, 62/85). Essentially the same results were seen with respect to efficacy of ovulation inhibition, rate of egg maturation, and fertilizability of the intrafollicular ova when ID was administered 30 min before hCG injection. These findings indicate that in the mouse, prostaglandins (PG), while required for follicle rupture, are not involved in the ovum maturation process, including fertilizability, under the experimental conditions employed.