THE INFLUENCE OF AGE ON SUPEROVULATION IN THE IMMATURE RAT AND MOUSE

Abstract

Studies on supcrovulation in the immature rat and mouse indicated that the average number of ova released following treatment with gonadotropins reached a maximum on 23 to 32 days of age for the former and 23 to 26 for the latter. Thereafter the number of eggs released decreased rapidly by 50 to 65% prior to puberty although the gonadotropin treatment was held constant. Treatment with higher dosages of gonadotropins (PMS + HCG) at 40 to 50 days of age induced the release of a larger number of ova leading to the conclusion that the decrease in the number of ova released with age was due to changes in the sensitivity of the follicles to the gonadotropins. It would appear that initially the follicles become competent to respond to the gonadotropins at approximately 14 days of age for the mouse and 17 to 18 days of age for the rat. The sensitivity increases to a maximum within two weeks and decreases thereafter.