Relaxin and Mammary Growth in the Mouse

Little or no increase in the percentage of positive mammary alveolar responses was obtained in ovariectomized mice treated with estrogen plus progesterone plus relaxin as compared to those treated with estrogen plus progesterone only. Progesterone inhibited the pelvic relaxing effect of estrogen or of estrogen plus relaxin. Neither progesterone nor relaxin exerted any significant modifying effect on the increased bone density resulting from estrogen administration.