THE SECRETORY CAPACITY OF THE AUTOTRANSPLANTED HYPOPHYSIS AS INDICATED BY THE EFFECTS OF STEROID HORMONES ON THE MAMMARY GLANDS

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Abstract
In the present experiments the secretory capacity of the pituitary gland, autotransplanted to the kidney capsule, was studied with special regard to the secretion of prolactin and growth hormone, using the response of the mammary glands to oestrone (3-hydroxy-oestra-l,3,5(10)-trien-17-one) and progesterone (pregn-4-ene-3,20-dione) in castrated female and male rats as indicator. The main results were as follows (1) Daily injections of 10 ug of oestrone + 4 mg of progesterone stimulated slight duct growth and marked but not maximal lobule-alveolar develop- ment in the mammary glands of rats with transplanted hypophysis. In rats with intact pituitary gland this treatment produced more extensive duct growth and more marked alveolar development. (2) Daily injections of 1 ug of oestrone did not stimulate mammary gland development in rats with transplanted pituitary gland. The same treatment produced slight but definite duct growth in rats with intact pituitary gland. (3) Daily injections of 10 ug of oestrone stimulated slight duct growth and restricted lobule-alveolar development in rats with transplanted hypophysis. In rats with intact pituitary gland this treatment produced more extensive growth of the duct system. (4) In hypophysectomized rats all dose levels of oestrone and progesterone were ineffective in promoting mammary gland development. Combined with prolactin these hormones stimulated, in hypophysectomized rats, a mammary gland development which, qualitatively as well as quantitatively, was very similar to that found in rats with transplanted pituitary gland. These results indicate that the transplanted pituitary gland secreted considerable amounts of prolactin but did not secrete growth hormone or secreted it in only very small amounts.