We studied the effects of different
hormones on the epithelial cells of the ovaries of 11 guinea pigs. Three received
testosterone, two received
estrone, three
megestrol, and three
chorionic gonadotropin. Three control guinea pigs received sterile water. Benign epithelial
cysts larger than 1.5 mm were found in six guinea pigs, three who received
testosterone, one who received
megestrol, and two who received
chorionic gonadotropin. In one of the three guinea pigs who received
testosterone, 2.5-cm bilateral
cysts were grossly identified. Papillary excrescences were found on the ovarian surface in four guinea pigs, three who received
testosterone and one who received
megestrol. The proliferating epithelial cells also formed benign glands in the ovarian stroma in two guinea pigs who received
testosterone, the most exuberant epithelial proliferations, including large bilateral
cystadenomas, papillary excrescence that formed a small papillary
neoplasm, and glands in the ovarian stroma that formed adenomatous areas, were seen in the guinea pig who received an intermediate dose of
testosterone for the longest time. By radioimmunoassay, the serum level of
testosterone was 22 ng/dL in one of the controls and 10,000, 12,000, and 15,000 ng/dL in the three guinea pigs who received
testosterone. In the guinea pig with the most exuberant epithelial proliferation, the level of
testosterone in the uterus was similar to that in the serum (13,860 ng/mg), but in the wall of the ovarian epithelial
cyst, it was three times higher than it was in the serum (44,000 ng/mg). Our study shows that
testosterone stimulates the growth of epithelial cells in the ovaries of guinea pigs, resulting in benign
cysts, small
adenomas in the ovarian parenchyma, and
papillomas on the ovarian surface. The study also shows that guinea pigs can be used as an animal model for epithelial
tumors of the human ovary.