INFLUENCE OF THYROXINE UPON MAMMARY LOBULE-ALVEOLAR GROWTH1,2

Abstract

Thyroxine in an optimal dose increased significantly the % of castrate [female] mice which responded with mammary lobule-alveolar growth to minimal doses of progesterone and estrone. The efficiency of progesterone and estrone in stimulating such growth was thus increased about 25% by the thyroxine. Thyroidectomy, on the other hand, inhibited the ability to respond to progesterone and estrone with mammary lobule-alveolar growth. A discussion of the possible mechanisms for these effects is presented.