222 STUDIES ON PATHOLOGIC OVA. 



begin before 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 hydatiform degeneration can precede the appearance of the villous 

 capillaries, vascularization of the villi may never occur. In older conceptuses, 

 however, in which vascularization of the villi has supervened, the first recognizable 

 change is the disappearance 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 123, 124, and 126, 

 and in figures 109 to 112, inclusive. 



Coincident with the disappearance of the vessels, also noted by Vecchi (1906) 

 in villi with vesicles only as large as a "millet" seed, 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 be splendidly preserved. The 

 latter may be one 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, its sparseness, 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, it 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 intracellular 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. 125) 

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

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

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

 More generally, however, the vacuoles or small fenestrs 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 

 or even formed by these large, erratic cells, which usually lie in fenestra? in the 

 stroma (fig. 127.) In other instances a large portion of the sections of the villi 

 may be occupied by them, as shown in figure 128. The presence of these cells 

 in villi regarded as normal has long been known. Their presence in hydatiform 



