Abstract
Summary
A comparison is presented of the biological activity of progesterone and 20β-hydroxy-pregn-4-ene-3-one with estradiol benzoate upon mammary gland growth of the ovariectomized rat. When 1 μg of estradiol benzoate (EB) plus 3 mg of progesterone (P) was injected, the mean DNA was 5.83 mg/100 g of body wt. When 1 μg of EB was combined with 3, 6, and 9 mg of 20β-ol, the mean DNA was 43, 34, and 32%, respectively, less. At the 9-mg level of 20β-ol only 68% as much mammary gland was stimulated as by 3 mg of P.
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