354 HYDATIFORM DEGENERATION IN TUBAL AND UTERINE PREGNANCY. 



the capillaries have appeared in the villi. There is some evidence which suggests 

 that it possibly may appear before this time. If so, it would be incorrect to speak 

 of a disappearance of the vessels in such chorionic vesicles, for if the advent of hydat- 

 iform degeneration can precede the appearance of the villous capillaries, vasculari- 

 zation of the villi may never occur. In older conceptuses, however, in which vascu- 

 larization of the villi has supervened, the first recognizable change is the disappear- 

 ance of these capillaries. Many specimens in which the latter were in various 

 stages of degeneration were examined carefully, and the opinion of Hewitt (1860), 

 that hydatiform degeneration can not arise in villi which have been vascularized, 

 can be regarded as of historical interest only. Different stages in the process of 

 vascular degeneration are represented in figures 33 to 35 inclusive. 



Coincident with the disappearance of the vessels, changes in the stroma also 

 are noticeable. Usually it tends to become glassy, the individual nuclei becoming 

 separated farther. The stroma, though apparently solid, is uniformly slightly 

 bluish and vitreous, with well-defined, rather small, pycnotic, pointed nuclei, but 

 with not a vestige of a vessel, though the epithelium is splendidly preserved. The 

 latter may be one-layered or two-layered, and may be accompanied by syncytial 

 buds and trophoblastic masses and nodules. In such specimens the entire picture 

 really is exquisite, and a mere glance through the compound microscope reveals 

 the lack of vessels in the vitreous stroma and the marked differences in size of the 

 sections of the villi. 



After these early changes, liquefaction of the stroma usually follows. As is 

 well known, liquefaction generally begins in the interior and first appears in the 

 form of vacuolation; but this vacuolation (which I can not regard merely as an 

 edema) is not intra-cellular but intercellular, and as it becomes more pronounced 

 it really takes on the nature of fenestration. Sections of the whole cross-section 

 of the villi, even though large, may be composed of a series of fenestrae (see fig. 36) 

 separated by exceedingly fine strands of the remaining stroma which may contain 

 remnants of the nuclei. But finally, even the fine trabeculse separating the fenes- 

 trae disappear, and the stage of the watery, old, hydatid condition has been reached. 

 More generally, however, the vacuoles or small fenestrse lying in the middle become 

 confluent at the center of the cross-section of the villus, which then is liquefied 

 completely. As is well known, this liquefaction gradually extends to the periphery 

 as the zone of the surrounding stroma is narrowed in the process. Not infrequently, 

 however, liquefaction of the stroma occurs quite generally throughout the cross- 

 section of the villus and is accompanied by the formation of numerous large cells, 

 the wandering or migrating cells of earlier writers. A few of these cells almost 

 always can be found, and rarely the whole section of the villus is studded with 

 (fig. 37) or even formed by these large, erratic cells which usually lie in fenestrse in 

 the stroma. In other instances a large portion of the sections of the villi may be 

 occupied by them, as shown in figure 38. The presence of these cells in villi regarded 

 as normal has long been known. Their presence in hydatiform moles was noted by 

 Otto, Marchand (1898), Essen-Moller, and by many others. Their occurrence in 

 normal and pathological chorionic vesicles, and their significance are considered 



