The dose of 15 IU PMSG was found to be optimal for inducing ovulation within 74 hours in 27-day-old immature female rats. There was a significant decrease in the mean number of ova per ovulating ...animal when the dose was raised beyond this (r = 0.6554, p less than 0.001 for the range from 15 to 100 IU), but the number of ovulating animals did not decrease unless more than 80 IU PMSG were injected. The PMSG-induced ovulation was not affected by treating the animals with 10 or 100 mug clomiphene citrate at 0, 24, 48, 54, 60, 66 hours or at 0, 24, and 48 hours.
