THE PITUITARY BODY 



may occur after parturition. Less frequently this may also 

 be observed in the ferret. In the pregnant rat, but not in the 

 pregnant ferret, growth of the mammary glands continues 

 after hypophysectomy.^ In the sections following this, it will 

 be pointed out that lactation may follow procedures such as 

 the removal of luteinized ovaries from rats, cesarean section 

 in ratSj etc. In several instances it has been shown that hy- 

 pophysectomy prevents the lactation ordinarily appearing 

 under such conditions. 



By the injection of extracts of the pars glandularis, lacta- 

 tion has been produced in the hypophysectomized rat, dog, 

 and ferret (Riddle and others, 1933; Lyons and others, 1933; 

 McPhail, 1935). 



THE EFFECTS OF THE LACTOGENIC HORMONE 

 IN MAMMALS 



The conditions suitable, in various mammals, for inducing 

 lactation either by the secretion of the lactogenic hormone or by 

 the injection of anterior-lobe extracts: i. The gonads and their 

 internal secretions.- — In their studies of the production of 

 lactation by the injection of an anterior-lobe extract into 

 rabbits, Strieker and Grueter concluded that no effect could 

 be produced in the adult female rabbit unless its ovaries had 

 at some time secreted corpus luteum hormone. In their first 

 experiments, pseudopregnant rabbits were used. Later they 

 produced lactation in spayed rabbits even months after 

 ovariectomy, but declared that this was possible only in case 

 such rabbits had previously been either pregnant or pseudo- 

 pregnant. From their results it would appear that the de- 

 velopment of the breasts, great enough so that an anterior- 

 lobe extract could stimulate the secretion of milk, depended 

 partly upon the secretion of progesterone (corpus luteum 

 hormone). However, Corner (1930) was able to produce 



^ CoUip, Selye, and Thomson (1933); Selye, Collip, and Thomson (1933-34); 

 JefFers (1935); and McPhail (1935). 



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