THE HORMONES IN HUMAN REPRODUCTION 



in all mammals, in the first days of pregnancy and also 

 without pregnancy, whenever a recent corpus luteum is 

 present in the ovary. This means that in animals with regular 

 cyclic ovulation, for example the guinea pig, dog, cat, pig, 

 human, and indeed most mammals, progestational prolifera- 

 tion occurs in each cycle. It is not exactly alike in all 

 animals ; it is very elaborate in some, such as the rabbit 

 and the primates (monkeys, apes, and humans) but in others, 

 e.g. rat, mouse, and guinea pig, it is relatively slight. Plate 

 XVII shows it in three kinds of animals. 



Ancel and Bouin guessed that this progestational pro- 

 liferation is caused by the corpus luteum, and they took 

 steps to prove it by an ingenious plan. They mated their 

 female rabbits, not to fertile bucks, but to males rendered 

 infertile by tying off their seminal ducts. Such rabbits 

 ovulated and formed corpora lutea but, of course, did not 

 become pregnant. The only respect in which they were dif- 

 ferent after mating was that their ovaries now contained 

 corpora lutea. Since their uteri developed typical progesta- 

 tional proliferation, the corpora lutea must have been re- 

 sponsible. The two experimenters then repeated their ex- 

 periment of mating their rabbits to infertile males, but 

 within a day or two they removed the ovaries or cut out the 

 corpora lutea. Progestational proliferation did not occur. 

 Obviously the corpus luteum controls the condition of the 



Plate XVII. Preparation of the uterus for implantation of the embryo 

 (progestational proliferation) in human, rabbit, and pig. In each case the 

 left-hand figure shows the interval stage, the right-hand figure shows the effect 

 of the corpus luteum hormone. A^ this process in the human uterus, from the 

 first description by Hitschmann and Adler, 1908. Magnified about 15 times. 

 B, the first pictures of progestational proliferation of the rabbit's uterus, by 

 Bouin and Ancel, 1910. Magnified about 10 times. C, the same change in the 

 uterus of the sow, from preparations by the author. The left-hand figure repre- 

 sents the day before ovulation, the right-hand section was taken 8 days after 

 ovulation. Magnified 10 times. 



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