324 Mammary Growth After Hypophysectomy 



uninjected hypophysectomized controls and maintain (on an average) their 

 preoperative weight, in contrast to a loss of about 17 gm. by the latter. Never- 

 theless, it was noted that minimal lobulo-alveolar growth was induced by lacto- 

 genic hormone and FSH in some hypophysectomized rats which had lost as 

 much weight as the controls and showed atrophic thyroids and adrenals at 

 necropsy. In this same connection it has been noted that hypophysectomized 

 rats injected with somatotrophic hormone may sometimes show bone growth 

 even though they experience a loss of body weight. 



It was possible to obtain complete lobulo-alveolar mammary growth in 

 hypophysectomized rats given 10 I.U. of estrone (or 5 R.U. of FSH) with 5 mg. 

 of a crude acid-acetone beef anterior-lobe extract, L351B, containing approxi- 

 mately 10 I.U. of lactogenic hormone per mg. Since a considerably higher 

 unitage of lactogenic hormone given in the pure form with estrone was quite 

 incapable of stimulating this degree of lobulo-alveolar development it would 

 appear that another pituitary hormone (or hormones) important for mam- 

 mary growth and not identified with the lactogenic is present in the crude 

 preparation. It should be recalled that in Astwood's experiments,^ luteo- 

 trophic and mammary-stimulating activities were not always found together 

 in the same extracts. Enough somatotrophin was present in our crude extract 

 to cause the hypophysectomized rats to grow at the rate of about 2 gm. per 

 day even at a i-mg. daily dose, while the 5 mg. daily dose maintained the 

 adrenals at about two-thirds of their normal weight. 



Further evidence for an unidentified pituitary factor or combination im- 

 portant for mammary growth was found in the doubly operated rats. Estrone 

 and progesterone caused slight lobulo-alveolar growth in hypophysectomized- 

 oophorectomized rats when given with lactogenic hormone, and good lobulo- 

 alveolar growth when given with the crude extract. The crude lactogenic 

 preparation caused no lobulo-alveolar growth when given to the doubly 

 operated animals with estrone or FSH. It is not possible to say, as yet, whether 

 a new hormone or the proper combination of lactogenic, adrenotrophic, and 

 somatotrophic hormones known to be present in the crude extract is capable 

 of rendering the hypophysectomized rat's mammary gland responsive to es- 

 trone and progesterone. A few experiments have already been carried out 

 which show that no one of the three mentioned hormones injected with estrone 

 will cause in the hypophysectomized rat the complete lobulo-alveolar growth 

 induced with estrone and the crude combination. 



Apparently the mammogen theory of mammary growth is not supported by 

 the data presented. A degree of lobulo-alveolar growth comparable to that 

 considered adequate for assaying mammogen IF" was induced in (a) hypophy- 

 sectomized rats injected with estrone and a pure protein* (the lactogenic hor- 

 mone) and (b) hypophysectomized-oophorectomized rats injected with estrone, 



* The pure lactogenic hormone used was made by essentially the same method as reported 

 in 1937.^^ We have shown that the hormone isolated by this method may be proven chemically 

 pure by solubility tests.^*" The acid-acetone extract obtained before the NH3 step was used as 

 the crude lactogenic preparation. 



