HORMONAL FACTORS 



835 



of adrenal cortical neoplasms (Dunning et al., 1953) by estrogen, that is, pituitary 

 secretion of tumorigenic gonadotrophin stimulated by the injection of estrogenic 

 hormone. 



Pituitary tumors have been induced in rats and mice by exogenous (Gardner and 

 Strong, 1940; Clifton and Meyer, 1956) and endogenous estrogen (Bielschowsky, 

 1954). Genetic factors are very important in determining pituitary tumorigenesis 

 of this type (Gardner and Strong, 1 940). The tumors may be largely chromophobic 

 (Gardner and Strong, 1 940) with some admixture of acidophiles (Bielschowsky, 

 1954; Clifton and Meyer, 1956); the hormone secreted by these tumors is 

 mammotrophic (Bielschowsky, 1954). Although the acidophiles have been as- 

 sociated with secretion of this hormone, in one series of experiments stimulation 

 of the mouse mammary gland occurred in mice bearing basophilic tumors (Dickie 

 and Woolley, 1949). 



Mammotrophin-secreting pituitary tumors have also appeared in mice receiving 

 heavy irradiation to the entire body (Furth, 1955). The mechanism of induction 

 remains obscure. Since the occurrence of ovarian tumors may precede pituitary 



OVARIAN-PITUITARY-MAMMftRY INTERRELATIONSHIPS 

 AS DEMONSTRATED BY PARABIOSIS (AFTER BIELSCHOWSKY) 



(3) PITUITARY HYPERSECRETION 

 OF GONADOTROPE 



(2) LOW BLOOD 

 LEVEL OF 

 ESTROGEN 



(I) OVARIECTOMIZE 



ESTROGEN 



DOES NOT CROSS 



BARRIER 



(6) MAMMOTROPHIN 

 STIMULATES 

 MAMMARY GLAND 



(5) HIGH BLOOD LEVEL 

 OF ESTROGEN YIELDS 

 PITUITARY ADENOMAS 



(4) OVARIAN STIMULATION 



ESTROGEN STIMULATED 

 UTERUS 



Fig. 27. Ovarian pituitary 

 endocrine interrelation- 

 ships involved in ovarian, 

 pituitary and mammary 

 tumorigenesis. 



neoplasms (Furth and Butterworth, 1936), estrogenic secretion may represent the 

 stimulus for pituitary neoplasia in at least certain instances (Fig. 27). Secretion of 

 mammotrophic hormone by the pituitary gland under the influence of estrogen may 

 be an important factor in mammary tumorigenesis (Miihlbock, 1 956) . Bielschowsky 

 et al., (1956) have studied an inbred strain in which acidophilic hyperplasia of 

 the pituitary gland is associated with mammary hyperplasia and neoplasia. 



(d) JVeoplasms of tissues whose normal growth is stimulated by estrogen 



The incidence of rnamrriary cancer is much higher in human females than males, 

 suggesting the probable importance of an endocrine status which characterizes 

 females. In inbred mice spontaneous mammary cancer occurs only in females 

 with the exception of one inbred strain in which testicular changes in the male 

 suggest an hormonal imbalance (Athias and Furtado, 1941). Similar alterations 

 in the testis may be induced by exogenous estrogen. 



Administered estrogen (Lacassagne, 1932) or ovarian (Fig. 32) transplantation 



Literature p. 870 



