THE PITUITARY BODY 



The effects of various hormones on the morphology of the 

 breast are well illustrated by figures reproduced from a re- 

 port by Anselmino, Herold, and Hoffmann (1935). All the 

 samples of breast tissue were removed from the same cas- 

 trated male rabbit after castration (Fig, 10, A) and after 

 treatment for nearly 4 weeks with oestrin (Fig. 20, 5), fol- 

 lowed by the daily injection of progesterone for 6 days (Fig. 

 20, C). Finally, extract containing anterior pituitary lacto- 

 genic hormone was administered for 5 days; lactation then 

 appeared (Fig. 20, D). 



THE LACTOGENIC HORMONE^" 



Provided that there is adequate development of the 

 breasts, the secretion of milk in normal mammals probably 

 takes place because of the release and continued secretion 

 of the lactogenic hormone of the anterior pituitary. How- 

 ever, this statement is not meant to exclude the participation 

 of other hormones, including, particularly, the adrenal corti- 

 cal hormone. After hypophysectomy, with which is associ- 

 ated a marked reduction of the activity of the rest of the 

 endocrine system, lactogenic hormone alone will not initiate 

 or support lactation, although the breasts may be suitably 

 developed or secreting milk at the time of operation. 



It is now proposed to discuss factors which influence, both 

 positively and negatively, the action or the conditions neces- 

 sary for the action of the lactogenic hormone. 



The effect of suckling on the secretion of lactogenic hormone. — 

 Selye, CoUip, and Thomson had earlier demonstrated that 

 the stimulus of suckling, without the escape of milk, main- 

 tains the secretion of lactogenic hormone, as shown by lacta- 

 tion in breasts from which the nipples had been excised." 

 Ingelbrecht's experiments (1935) indicate that the reflex 



■" Synonymous terms are galactin, mammotropic hormone, and prolactin. 



" In the guinea pig, unlike the rat, ligation of the galactophores is rapidly fol- 

 lowed by failure of lactation in the corresponding breast, although suckling and 

 lactation continue in the other breast with a normal nipple (Hesselberg and Loeb, 



1937)- 



