POST-MORTEM INTRAUTERINE CHANGES. 285 



vesicles could lead to obliteration of vessels. In the chorionic vesicle the picture 

 presented is that of migration rather than that of proliferation, and it is indeed a 

 long step from these things to complete obliteration of blood-vessels, especially 

 when it is recalled that the latter involves the growth of new capillaries, as was 

 reported by Merttens and as is the case in the normal postnatal obliteration of the 

 umbilical vessels. Schickele (1907) also observed obliteration by endothelial 

 proliferation in the various vessels, but insisted that they do not occur with the fre- 

 quency reported by Merttens. Schickele further stated that obliteration occurs 

 rapidly and that it is not necessarily post-mortem. 



Waldstein, who made a very careful histologic examination of some abortuses, 

 stated that, although the regressive changes had not yet been sufficiently studied, 

 he did not believe in a continued growth of the embryo, but merely in a further 

 differentiation of some of the constituent tissues, and also in a round-cell infiltra- 

 tion. Waldstein claimed that in some specimens examined by him the striations 

 in the central musculature were maturer than they should have been, and hence 

 concluded that post-mortem differentiation had taken place in them. He believed 

 that the round cells had an intravascular origin. Boerma (1912), who described 

 a young macerated embryo, also stated that the amniotic cavity contained cell- 

 masses from the embryo which he believed had survived the parent mass. 



His (1891), Giacomini (1894), Schaeffer (1898), Mall, and the writer occasion- 

 ally found local thickenings of and adhesions between certain epidermal surfaces. 

 These adhesions and thickenings, referred to in Chapter IV, group 7, were present 

 in the lower extremities of the fetus shown in figures 64 and 65 (plate 5, Chap. IV). 

 In this case, as in those of Lomer and Schaeffer, the extremities are glued together 

 by epidermis. The appearance of the lower extremities at this point also suggests 

 that there has been an accumulation of sloughed epidermis in the region of contact. 

 To what extent this gluing is due to fusion of dying tissues and cells, rather than 

 to growth, it is difficult to say. In other cases, as stated by His (1891), the extremi- 

 ties may be glued to the trunk, or the head to the chest, as observed also by Mall 

 and as illustrated in figure 176. The mandibular region may adhere to the chest 

 and the lips coalesce so completely that the epidermis is absolutely continuous 

 from the chest to the chin and also across the lips, as represented in section in 

 figure 180. 



Giacomini (1889) further described invaginations of the epidermis into the 

 mesoderm on the dorsum, lateral to the spine in an atrophic embryo 5 mm. long. 

 Although not regularly symmetrical, these epidermal invaginations nevertheless 

 were said to have a metameric arrangement, there being 6 on the right and 10 on 

 the left side. Giacomini stated that these epidermal growths reminded him of the 

 lateral-line organs of elasmobranchs, and added that he saw them at the caudal 

 extremity of another specimen. Epidermal accumulations in various places were 

 noticed also by Mall in long-retained cyemata, but nothing justifying Giacomini's 

 interpretation was encountered either by Mall or myself. The accumulations 

 noticed by us were small, irregular, and rather poorly preserved mounds of epider- 

 mis, as illustrated in figures 76 and 77. 



