CHAPTER XV. 



THE VILLI IN ABORTUSES. 



As long ago as 1832 Seiler stated that, although he could not be certain from 

 a magnification of 40 diameters, he did not think that chorionic villi were hollow. 

 Although Seiler concluded even at this time that villi are filled with cellular tissue, 

 the idea that they are hollow nevertheless persisted up to 1889. Seiler thought 

 that the first vessels invaded the villi as late as the third month. He represented 

 individual villi from chorionic vesicles from the fourth, fifth, and twelfth week as 

 clubbed in form, and also pictured several good villous trees. It is of particular 

 interest that he also represented a branching villus ending in a spherical termina- 

 tion, which suggests the "Zellknoten" of Kastschenko. 



Muller (1847) claimed that villi may grow until they are 2 inches long by the 

 fifth month, at which time he thought they still might cover two-thirds of the 

 entire surface of the chorionic vesicle. However, Muller's statement that the 

 villi are often cystic indicates quite clearly that he was not dealing with wholly 

 normal material, and that he probably saw degenerate or even hydatiform speci- 

 mens. 



Robin (1854) apparently assumed that normal villi are hollow, for he stated 

 that fibrous, fibrinous, scirrhous, tubercular, fatty, and calcareous changes of the 

 placenta are made possible by fibrous obliteration of the cavities present in normal 

 villi. Robin believed that such changes as these normally occur in the non-pla- 

 cental portion of the chorionic vesicle, and stated that unbranched and degenerate 

 villi are found in placenta? of all ages. From his descriptions one may conclude 

 that Robin noticed both the fibrinoid and the decidual layers of the placenta and 

 possibly also the presence of so-called infarcts. 



According to Winckler (1872), Bidder, Jr., showed that the villi are especially 

 densely set and particularly thick in caliber at the margin of the placenta. Winck- 

 ler himself distinguished three kinds of villi. He stated that atrophic villi are 

 found everywhere, and that they never penetrate the maternal tissues beyond 

 the closing plate (Schlussplatte) described by him. These villi, which were said to 

 reach the cavernous spaces of the decidua, he declared to be uncovered by epithe- 

 lium. Indeed, Winckler believed this to be true also of all other villi as long as 

 they had not penetrated the closing plate of maternal tissue, into which his second 

 class of villi were said to continue considerable distances without branching. 

 He believed that the villi obtain a covering of epithelium only after they reach 

 the cavernous spaces or blood-sinuses. His third class of villi, which also were 

 said to be devoid of epithelium as long as they lay in the maternal tissue, differed 

 from the second class only through their greater development. 



Langhans (1877) emphasized the irregularities in the villi which had been men- 

 tioned by Muller, and concluded that villi always are vascularized. 



Kolliker (1884) was especially impressed by the fact that the form of the villi 

 varies so greatly that one can hardly make any generalizations. He found that 



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