CHORION WITHOUT AMNION OR CYEMA. 67 



implanted undisturbed. The villi in some of these implanted specimens were so 

 characteristic, and the whole picture so exquisite, that these specimens rightly 

 belong among the very finest instances of hydatiform degeneration found among 

 all specimens, both tubal and uterine. 



Many of the tubal specimens are remarkable indeed, and this is true in particu- 

 lar of a case of double-ovum twin pregnancy received from Dr. Cecil Vest. In 

 this specimen the two chorionic vesicles, the intervillous spaces of which were 

 devoid of blood, lay in almost the same transverse diameter of the tube, and hence 

 had distended the latter considerably. Both were implanted quite well over the 

 entire area of contact, which included the whole perimeter of the tube. The 

 chorionic vesicles were flattened at the region of mutual contact, which divided 

 the tube somewhat unequally, as shown in figure 13, one of the original drawings. 

 Although the cyema and the amnion had long disintegrated completely, and 

 although the chorionic membrane itself is thin, covered by degenerate epithelium 

 and also disintegrating, the epithelium of the villi not only is well preserved, but 

 is accompanied by large masses of trophoblast and considerable syncytium. 

 Syncytial buds are found on the chorionic membrane also. The tubal mucosa is 

 largely, and the tubal wall partly, destroyed by the invading trophoblast. Only a 

 few small vestiges of the walls of the villous vessels remain, and the stroma of all 

 of the villi has undergone changes characteristic of hydatiform degeneration. 

 One villus also contains an epithelial cyst resulting from epithelial imagination 

 with subsequent isolation of the distal extremity, a process to be referred to again in 

 connection with the uterine specimens. Since most of these villi still are implanted 

 in the tube, there no longer can be any question as to the conditions under which 

 hydatiform changes in the stroma of the villi are inaugurated. As illustrated in 

 previous instances in which isolated and small groups of villi were still implanted, 

 the advent of degeneration of the stroma usually, if not always, occurs, in part at 

 least, before the villus is detached. Hence it is not merely a maceration change. 



As shown in section in figure 14, some exceedingly fine hydatiform villous 

 trees were found among the specimens in this group. Scaffoldings or frameworks, 

 formed by the proliferating sycytium arising from the epithelium of the chorionic 

 membrane, were also seen. Since syncytial buds were found far out on prolifera- 

 tions of trophoblast which capped the villi, and also in the center of trophoblastic 

 nodules, the origin of the syncytium from the Langhans layer would seem to be 

 exceptionally well illustrated. In some cases a detached hydatiform villus was 

 fastened to two portions of the tube-wall. It is well to remember, however, that 

 these attachments may have been gained, and indeed probably were gained, 

 before the separation of the particular villus from the chorionic vesicle. 



In most of the cases of tubal specimens belonging to this group and not show- 

 ing hydatiform change, the few isolated villi were so degenerate, or necrotic even, 

 that no diagnosis of any kind would seem to be justified. In these instances the 

 partly or wholly collapsed chorionic vesicle also was very degenerate and usually 

 folded extremely, the folds radiating more or less from the unfolded portion of the 





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