MAMMARY GLANDS IN ENDOCEIN RELATIONSHIPS 645 



Uterine Hormones and Mammary Activity 



The Mammary Hyperplasia of Pregnancy. The possibility that the 

 uterus, among other tissues, is concerned in the mammary growth during 

 pregnancy has been brought into question. Although Fellner obtained an 

 indeterminate effect as the result of injecting extracts of pregnant uteri, 

 neither he nor Lane-Claypon and Starling were able to demonstrate that 

 uterine extracts stimulate mammary growth, and the probability that the 

 uterus per se exerts an influence during this period is minute. 



Milk Secretion and the Uterus. Clinical evidence is ample to show 

 that postpartum hysterectomy is not necessarily followed by cessation of 

 lactation. Halban, Foges and Lambret have presented cases demonstrat- 

 ing that milk secretion may continue even though the uterus be absent. 

 Since MacKenzie obtained a decided galactagogic effect by the injection 

 of saline extracts of the involuting uterus, it is not improbable that the 

 tissue at this stage does give off metabolic by-products that are stimulating 

 to mammary secretion. This, however, does not necessarily signify that 

 a normal function of the uterus is the production of a hormone excitatory 

 to lactation. 



The Placental Hormone and the Mammae 



In the chapter concerned with the Placenta as an Endocrin Gland 

 there will be found a discussion of the hypothesis built up around the 

 ideas of the effect of placental secretion on mammary growth during preg- 

 nancy, and their secretory activity. 



The Fetus and Mammary Activity 



With the onset of conception commences the growth of the mammary 

 glands preparatory to their taking on of the function of lactation, though 

 it is not until the delivery of the uterine contents that this function 

 normally is assumed. It is but natural that investigators have looked to 

 the fetus as a possible source of the stimuli bringing about both the growth 

 and subsequent lactation. 



The Fetus and Mammary Growth during Pregnancy. Although 

 Halban (1905) on clinical grounds, and Frank and linger on the basis 

 of experimental results, consider that the fetus is not concerned in the 

 mammary hyperplasia of pregnancy, the investigations of Lane-Claypon 

 and Starling, which have been amply confirmed by Foa and by Biedl and 

 Ko'nigstein, show unmistakably that injections of fetal extracts will pro- 

 duce a growth of mammary tissue analogous to that occurring during 

 pregnancy. These results, by a process of eliminative experimentation, 



