UTERINE, TUBAL AND OVARIAN LYSIS AND 

 RESORPTION OF CONCEPTUSES. 1 



ARTHUR WILLIAM MEYER. 



It has long been known that considerable intrauterine retro- 

 gression of a conceptus can occur in multiparous mammals. 

 D'Outrepont, for example, on page of the 192 catalog of his 

 collection, is said to represent the uterus of a rabbit, in which 

 an apparently full term fetus is found near the distal end of one 

 horn, although the approximate portions of both horns contained 

 nothing but remnants of fetuses one in each. According to 

 Muller, '47, the enlargement in the right horn contained a 

 "cyst filled with rabbit hair imbedded in a soft mass and that 

 on the left side a similar convolute of hairs without a cyst." 

 This, as far as I know, is the earliest reference to, even if not the 

 earliest observation upon a fetal retrogression. But since rabbits 

 are born naked, one is left to speculate upon the validity of this 

 observation. However, that the idea holds is indicated also by 

 some experimental work. Sokoloff's, '96, meager report, for 

 example, seems to indicate that in dogs bilateral ovariotomy 

 leads to the death of the embryo and to abortion of it and of the 

 entire conceptus. Strahl and Henneberg, '02, also found that 

 conceptuses in different stages of retrogression occur quite 

 commonly among normally developed ones in the ferret, marmot 

 and mole. They also found that the entire placenta and prob- 

 ably also the fetal membranes, as stated by Hubrecht, normally 

 are retained for some time, even up to a month after parturition 

 in the mole. Similarly, Frankel, '03, was able to cause the death 

 and also the uterine absorption of conceptuses in rabbits up to 

 the 2oth day of pregnancy, through destruction of the corpora 

 lutea. Frankel found that after 14 days, all that remained in 

 the way of evidence of some pregnancies was an anemic ring 

 which disappeared completely within three weeks. Henneberg, 



1 From the Department of Embryology of the Carnegie Institute and The De- 

 partment of Anatomy of Stanford University. 



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