CYCLIC CHANGES IN UTERUS AND OVARIES. 3! 



V. THE INFLUENCE OF EXTIRPATION OF THE CORPORA LUTEA 

 ON THE DURATION OF THE CYCLIC PERIOD. 



I have previously shown that the duration of the sexual period 

 in the mammalian female depends upon the duration of life of 

 the corpus luteum. 1 The corpus luteum prevents a new ovula- 

 tion and the onset of a new sexual cycle. 



In our former experiments some operative interference had 

 usually taken place in the case of the control guinea-pigs as 

 well as in those in which the corpora lutea had been excised. It 

 was therefore necessary to determine the length of the sexual cycle 

 in the normal guinea-pig. This can be done by observing the 

 time of the heat of a guinea-pig and by examining uterus and 

 ovaries at known intervals. Under those conditions we found 

 the length of the sexual period to be usually sixteen to eighteen 

 or nineteen days; sometimes the new ovulation may take place 

 as early as fifteen days after copulation. In two exceptional 

 cases we observed the new ovulation as early as thirteen and a 

 half to fourteen and a half days. If we allow copulation to take 

 place and ligature the tubes at their juncture with the uterus, 

 and in addition, the upper part of the uterus, within the first 

 two and a half days after copulation, the new ovulation also 

 may take place between the sixteenth and eighteenth day, but 

 in other cases it occurs later. If we make incisions into the 

 uterus throughout its whole length five to seven days after 

 copulation, ovulation takes place in the majority of cases between 

 the twentieth and thirtieth day after copulation. At the times 

 ovulation occurs the corpora lutea of the previous sexual period 

 have begun to degenerate and the experimentally produced 

 placentomata have to a great extent become necrotic. The 

 beginning degeneration of the corpora lutea is a prerequisite for 

 the new ovulation. If, after copulation, pregnancy is permitted 

 to take its normal course, no ovulation occurs until birth has 

 taken place. If abortion has taken place, a new ovulation also 

 can occur. 



If we excise the corpora lutea within the first week after 

 copulation, a new ovulation occurs in the majority of cases 



1 Zentralblattf. Physiologic, Bd. XXIII., No. 3, Deutsche Med. Wochenschrift, 1911 , 

 No. i. 



