THE EFFECTS OF HYPOPHYSECTOMY 



most part these experiments deal with (a) the oxytocic prin- 

 ciple, and {l>) the principle responsible for diuretic-antidiu- 

 retic effects. However, parturition takes place in the hypo- 

 physectomized dog or in the dog from which the posterior 

 lobe has been removed (Aschner, 191 2; Dott, 1923). More- 

 over, the metabolism of water may remain unchanged in the 

 hypophysectomized dog (Houssay and Hug, 1921; Houssay 

 and Mazzocco, 1922). As was mentioned before, the blood 

 pressure of the dog may fall after hypophysectomy, but not 

 after the removal of the posterior lobe. There is, therefore, 

 little evidence in favor of the view that the pars neuralis (or 

 posterior lobe) is physiologically important. The interpreta- 

 tion of the data is intimately connected with the interpreta- 

 tion of the effects of hypothalamic lesions and will therefore 

 be postponed (pp. 71-79). 



The effects of hypophysectomy in other mammals. — Selye, Col- 

 lip, and Thomson (1933) studied the effects of hypophysec- 

 tomy in pregnant and lactating mice. Apparently normal 

 parturition occurred in mice from which the pituitary was 

 removed in the latter half of pregnancy; the young, which 

 appeared normal, were probably still-born. Milk was se- 

 creted by the mothers only for a short time postpartum. 

 Hypophysectomy in lactating mice prevented the secretion 

 of milk within 24 hours after the operation. In hypophysec- 

 tomized mice, unlike hypophysectomized rats, the corpora 

 lutea did not persist, but regressed rapidly. 



The technique of hypophysectomy in the guinea pig has 

 been described by McPhail and Parkes (1933), Anselmino 

 and Pencharz (1934), and Macchiarulo and Amelotti (1934). 

 Pencharz and Lyon (1934) hypophysectomized pregnant 

 guinea pigs. In animals subjected to operation on the thirty- 

 fourth to the thirty-sixth day, resorption of the fetuses began 

 within two days. If the operation was performed on the for- 

 tieth to the forty-first day of pregnancy, the period of gesta- 

 tion was not significantly altered (63-67 days); however, 



[67] 



