322 STUDIES ON PATHOLOGIC OVA. 



tree, to the right of which there also are some macerated villi and to the left others 

 fused by trophoblast. The contrast in form, surface, and appearance between 

 the hydatiform and the normal villous tree is very striking indeed, and it would 

 seem that the hydatiform villus largely loses its power of branching, and, except 

 for local increases in caliber, grows mainly in length. 



A somewhat older, apparently normal chorionic vesicle with normal villi is 

 No. 2361, shown in figure 256. In this vesicle, which measures 35 by 35 mm. and 

 which has an age of about 4J^ weeks, some of the villi in the basal area are very 

 plainly hydatiform, although also macerated. Both of these changes are notice- 

 able also in some degenerated villi shown in figure 257, but inspection of the cap- 

 sular area of this chorion shows that no hydatiform change is evident here, nor 

 is it evident on the external surface of the abortus represented in figure 258. This 

 is due to the fact that the process is in its early stages, and because the conceptus 

 is surrounded by decidua. Although the specimen has a menstrual age. of 124 

 days, the abnormal embryo (shown in figure 206, plate 18, Chap. XIII) is but 

 3 mm. long and the chorionic vesicle only 35 mm. in diameter, measurements which 

 indicate anatomic ages of 4^ and 6J/2 weeks, respectively. Hence, if the menstrual 

 age can be relied upon, this specimen must have been retained 80 days. This does 

 not imply, however, that the chorionic vesicle necessarily had been dead during 

 all this time. Judged by the menstrual age, the fetus should be 150 mm. long, and 

 as judged by the chorionic diameter it should be 13 to 14 mm. long instead of 3 

 mm., its actual length. 



A second good example of the development of hydatiform degeneration, 

 especially in the area of the basalis, in vesicles of this size is found in No. 2077 

 (represented in fig. 101, plate 8, Chap. IX). This vesicle, which measured 40.5 

 by 28.5 by 18.5 mm., was reflected from the underlying decidua, but was never- 

 theless left attached to it so as to expose a large field of exquisite hydatids, a portion 

 of which is shown in focus in the center of the figure. 



The eiderdown appearance due to maceration changes, which was referred to 

 above and which is produced especially by post-partum maceration, is shown par- 

 ticularly well in No. 993, a portion of which is represented in figure 259. The only 

 possibility of confusion of these changes with other conditions is that one might 

 take an instance like this for intrauterine lysis, but usually other criteria will 

 enable one to differentiate the two conditions. However, when the two conditions 

 are associated such differentiation may become impossible. How very complicated 

 the branching of the villi has already become in these vesicles of the sixth week, 

 of a measurement of about 48 by 41 by 15 mm., is shown by the bush-like villus 

 represented in figure 260. The thick main stem of this villus stands out in marked 

 contrast to some of the branches, many of which are exceedingly fine and others 

 matted and fused. Fine, thread-like villi are common, especially in the area of 

 the chorion laeve, as early as the sixth to seventh week. This is exemplified well 

 by the specimens shown in figure 261. However, these fine villi, which usually 

 have a fibrous, non-vascular stroma, occur also in long retention and elsewhere 

 on the vesicle than in the area of the chorion laeve. They are present in the macer- 



