Date of Award


Degree Name

Master of Arts


Biological Sciences

First Advisor

Dr. Jack S. Wood

Second Advisor

Dr. Gordon W. Duncan

Third Advisor

Dr. Ronald J. Ericsson

Access Setting

Masters Thesis-Open Access


The effect of neonatally administered testosterone propionate (TP) on sexual receptivity and fertility was studied. Dosages of 25 μg and ten μg were used and were administered s.c. in peanut oil on the fifth day of life. Vaginal smears of the animals receiving 25 μg were begun at the age of 61 days and indicated that these animals exhibited modified estrous cycles. By 90 days of age, most of the animals in both dosage groups were in constant vaginal estrus. These prolonged periods of vaginal estrus were often interrupted only by mating.

At 97 days of age 40 females which received ten μg of TP were caged individually with males for six nights and 40% mated. At this same dose, out of 128 exposures, 42% of the females bred when exposed to males for one night. The latter group received 15 I.U. of chorionic gonadotropin (HCG) on the day of mating. In females receiving 25 μg of TP, out of 481 exposures, 33.6% of the animals mated. Eighty-nine per cent of the females which copulated had a vaginal smear consisting primarily of leukocytes the following morning.

Mating did not induce ovulation but ovulation did result after the administration of 15 I.U. of HCG. Priming with two mg of progesterone two days prior to caging with the male did not induce ovulation, nor did it enhance ovulation after mating.

The progesterone and 20 alpha-hydroxy-pregn-4-en-3-one content of ovaries removed from females which had ovulated with HCG was determined. Ovaries were taken for five days post-mating. The 20 alpha content showed a decrease from day one through day five while the progesterone content went from a peak on day one to a non-detectable level on day two. There was a slight increase from day three through day five.

Thirty-five animals from each dosage group were given 15 I.U. of HCG on the day they were placed with the male. These 35 animals were then subdivided into three groups: (I) ten animals received two mg of progesterone per day for 20 days; (II) ten animals received four mg of progesterone for 18 days; (Ill) fifteen animals received no progesterone replacement therapy. There were no pregnancies in either of the two dosage groups and thus progesterone replacement therapy had no effect on fertility.

Included in

Biology Commons