Endometrial Changes after Prolonged Progesterone and Testosterone Administration to Rabbits

Summary

Rabbits treated with large doses of progesterone for up to 763 days developed numerous cysts of the endometrium, sometimes associated with atypical hyperplasia. Active mammary secretion also occurred. After large doses of testosterone for up to 763 days 1 animal developed 2 adenomatous polyps of the endometrium, but there were no other noteworthy endometrial changes. Neither hormone produced significant alterations in other tissues including ovary, adrenal, thyroid, or pituitary gland. No precancerous endometrial changes or cancers were found.