THE PITUITARY BODY 



tioned whether or not the corpora lutea appearing after pro- 

 lan injection were truly functional corpora lutea. In the rat, 

 as well as in other animals, there is good evidence that the 

 corpora lutea so produced really do secrete progesterone. For 

 example, Shelesnyak (1933) showed that deciduomata could 

 be produced in immature rats, particularly if the uterine irri- 

 tation (threading) was begun about the fifth day of the injec- 

 tion period. 



Boeters (1931) and Zondek (1932), but not Mahnert 

 (1930), have observed pregnancy in immature rats mated 

 after the injection of prolan. 



The type of ovarian response also depends upon the age of 

 the rat. Wiesner (1932) administered prolan to very young 

 rats (newborn to 2 days of age) and could produce no ovarian 

 response. According to Dorfmiiller and De Fremery (1932) 

 the injection of prolan into rats 10 days old caused ovarian 

 and uterine growth; in the ovaries the interstitial tissue was 

 particularly prominent, but there were no follicle-ripening 

 and corpus luteum formation. Collip, Selye, and Thomson 

 have also investigated the effects of prolan administered to 

 young rats." If injections of prolan were begun during the 

 sixth to the sixteenth day of life, oestrus was present almost 

 continuously; but the only prominent ovarian change was a 

 luteinization of theca cells. The ovarian response remained 

 unchanged if injections were continued to the twenty-sixth 

 day; whereas if injections were not begun until the twenty- 

 first day, typical follicular development and formation of cor- 

 pora lutea atretica occurred. Luteinization of theca cells is 

 the prominent change produced in the ovaries of hypophysec- 

 tomized rats which have received prolan. Collip and his co- 

 workers believed that an anterior pituitary secretion (par- 

 ticularly that causing ripening of follicles) necessary for facili- 

 tating the usual ovarian response of older animals is not avail- 



" Collip, Selye, and Thomson (193J); Selye, Collip, and Thomson (1933, 

 1935); and Selye and Collip (1933). 



[ 190] 



