5 1 8 Mammary Growth After Hypophysectomy 



tempts have been made to cause mammary growths in hypophysectomized 

 rats with the sex hormones have yielded negative resuUs (see Folley/ Turner/ 

 and Petersen'" for reviews of this subject). In 1935 Selye and CoUip" reported 

 that estrone did not prevent the rapid involution of the hypophysectomized 

 rat's mammary gland. Later'^ they tried substitution therapy with crude pitui- 

 tary extracts and estrone, but apparently produced too little mammary de- 

 velopment to be considered significant. They concluded that the pituitary 

 extracts given with estrone produced no more development than estrone alone 

 in hypophysectomized rats, but postulated that the ovarian hormones act 

 upon the mammary gland indirectly by way of their pituitary-stimulating ef- 

 fect. Gomez, Turner and co-workers" '^ believe that estrin and progestin do not 

 act directly upon the mammary gland as was formerly thought (estrin caus- 

 ing duct growth and estrin combined with progestin causing lobulo-alveolar 

 growth), but that a pituitary hormone (mammogen I) stimulated to increased 

 secretion by estrin causes duct growth and a second (mammogen II) stimulated 

 to secretion by progestin plus estrin causes lobulo-alveolar growth. Lewis and 

 co-workers" obtained duct growth in hypophysectomized female rats (25-40 

 days old) by injecting for ten days what they claim to be a lipid-soluble mam- 

 mogen I extracted from cattle pituitaries. Their illustrations show that they 

 restored the glands from the regressed condition observed after hypophysec- 

 tomy. Greep and Stavely'° were able to demonstrate mammary-duct growth in 

 hypophysectomized immature female rats injected with pituitary dry powders 

 suspended in saline, but not with ether-alcohol extracts of dried or wet pitui- 

 taries. Mixner and Turner'* induced comparable lobulo-alveolar mammary 

 growth in spayed virgin mice by injecting either 400 mg. of pituitary suspen- 

 sion which contained mammogen II, or 0.5-1.5 mg. of progesterone plus 133 

 I.U. of estrone. 



Other investigators believe that duct and alveolar growth of the mammary 

 gland may still depend upon the ovarian hormones (as is suggested by the 

 fact that the proper dose of estrin applied locally to a mammary gland causes 

 only that and no other gland to grow)," but that these hormones will not stimu- 

 late mammary growth in the hypophysectomized animal unless some of its 

 multiple deficiencies are corrected. Astwood and co-workers'* showed that in- 

 tact rats restricted to a food intake equal to that of hypophysectomized animals 

 failed as did the latter to show mammary growth when injected with estrin. 

 Samuels and co-workers'" attempted to correct some of the deficiencies of the 

 hypophysectomized rat by force-feeding a diet supplemented by NaCl, adreno- 

 cortical extract, and thyroid. Their animals gained in weight, but failed to 

 show mammary growth in response to injections of 1,000 I.U. of estradiol 

 benzoate every other day for twenty-eight days. Nelson and Tobin'" injected 

 their hypophysectomized rats with crude anterior-lobe extract plus estrin and 

 obtained lobular mammary growth. Purified lactogenic hormone plus estrin 

 had "little effect." Uyldert and co-workers"' obtained mammary growth when 

 estrin and progestin and a pituitary extract were injected into hypophysecto- 



