Kaisa Turpeinen 



5^1 



it seemed interesting to test whether progesterone, the hormonal product of 

 corpora lutea, has any effect on the length of pregnancv during lactation. 

 Mirskaia and Crew* have postulated that the activity of the corpus luteum 

 might be insufficient to meet the requirements of both lactation and pregnancv 

 at the same time and that this might be the cause of the prolongation. There 

 is, however, some experimental evidence to the contrary. Thus, Teel" in his 

 experiments was able to produce delayed implantation in pregnant rats with 



TABLE 1 

 Effect of Progesterone in Prolongation of Pregnancy During Lactation 



Mouse No. 



20 

 21 



27 

 46 

 .18 

 17 

 42 

 24 

 26 



46 



anterior-pituitarv extracts ^\•hich caused luteinization of the ovaries. Pincus," 

 also reported a prolongation of pregnancy in lactating mice by injections of 

 estrone-free corpus Itueum hormone during the five to eight days after the 

 first parturition. He concluded that the excessive corpus luteum secretion 

 caused the delayed implantation during lactation. 



The source of corpus luteum hormone used in the present work -vvas "Lu- 

 tren." a preparation of synthetic progesterone in oil, manufactured by Bayer 

 I. G. Farbenindustrie (Leverkusen, Germany). The results are represented 

 in table 1. 



From this table it appears that when progesterone "^vas given during lacta- 

 tion, before the expected implantation, from the third to the seventh day after 

 the first delivery, a prolongation of pregnancy ensued, which in all cases except 

 one (mouse no. 26) was longer than anticipated if only lactation had caused 

 the delav. 



TJie Effect of Hypophysial Lactogefiic Hormone upon Prolongation of 

 Pregnancy During Lactation. Originally, anterior pituitary lactogenic hor- 

 mone was connected with the process of lactation. Later several new properties 

 were ascribed to this same hormone. DreseP" observed a distinct suppression 



