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Scientific Proceedings (132) 



lowing hysterectomy, there is usually no remnant of retro- 

 gressing corpora lutea representing former ovulations visible. 

 In one case, however, we found such a body side by side with a 

 well preserved corpus luteum. This was probably due to the 

 fact that one of the corpora lutea formed during an ovulation 

 may retrogress earlier than the others. 



We see then that extirpation of the uterus does not prevent 

 ovulation as such, but that it has such an effect only indirectly 

 by preserving the life of the corpora lutea. Also in other re- 

 spects the ovaries in hysterectomized guinea pigs are normal. 

 Follicles grow in the normal manner, mature and undergo 

 atresia. The maturation of follicles is not interfered with under 

 those conditions. 



These corpora lutea not only live, but they also function. 

 They prevent the occurrence of an ovulation during the whole 

 period of their life; but if the corpora lutea are extirpated com- 

 pletely, a new ovulation takes place at an early period notwith- 

 standing the absence of the uterus. This is an additional proof 

 that the hysterectomy as such does not prevent ovulation. On 

 the other hand, if we prevent the maturation of follicles through 

 underfeeding, a new corpus luteum does not develop in a young 

 guinea pig, which has not yet ovulated, even after extirpation 

 of the uterus. 



This marked prolongation in the life and function of the 

 corpus luteum may not only be obtained after a complete 

 hysterectomy, but even in cases in which a very small amount 

 of uterine tissue has been left back, an amount sufficient to give 

 rise to the development of a placentoma. In such a case we ob- 

 served as late as forty-six days after ovulation mitotic prolifera- 

 tion in placentomatous tissue without the presence of pregnancy. 



In these hysterectomized animals the mammary gland de- 

 velops quite markedly and mitotic proliferation may be observed 

 in such glands as late as seventy-four days after the last ovula- 

 tion. In one case we found sixty days after ovulation milk 

 production in a mammary gland which had previously prolifer- 

 ated. During the prolonged period of function of the corpus 

 luteum prooestrus and oestrus are prevented and thus growth 

 processes do not occur in the vagina. The epithelium of the 

 vagina becomes therefore very vacuolar and polynuclear leuco- 

 cytes migrate through the mucosa into the lumen in hysterec- 

 tomized guinea pigs. 



