THE PLACENTATiON OF PERAMELES. 419 



1. Uterus. — The serosa and muscularis are of about the 

 same thickness as in the non-gravid uterus. The muscularis 

 is penetrated by numerous large vessels. 



As in previous stages, the whole mucosa is folded^ the folds 

 being especially marked in the placental area. 



Corium beneath Allantoic Placental Area. — This 

 portion of the corium now differs markedly in appearance and 

 character from the remainder, being as a whole much denser 

 and more compact-looking; and its component parts — inter- 

 glandular connective tissue, uterine glands, and blood-vessels — 

 have all undergone important modifications. 



In tlie preceding stages we have seen that the connective 

 tissue of the whole corium consisted of a very delicate retiform 

 tissue. Now, however, in this region the connective-tissue 

 cells have not only increased in number, but also very greatly 

 in size. From the large, usually rounded, deeply staining cell 

 bodies less deeply staining processes pass off, which anastomose 

 with similar processes of adjacent cells to form a much coarser 

 and closer network than that seen in preceding stages, or 

 even in the corium outside this region in the present stage 

 (fig. 26, c. r.). 



There can be no doubt that we have here to do with a 

 process of proliferation of the connective-tissue cells beneath 

 the placental area, accompanied by their subsequent hyper- 

 trophy. 



This proliferation and overgrowth of the connective tissue in 

 Perameles offers interesting points of comparison with the 

 formation of the decidual cells in the pregnant human uterus, 

 which arise, as Minot has rendered certain, by the direct 

 proliferation and enlargement of the anastomosing connective- 

 tissue cells of the mucosa (4, p. 419). 



Numbers of polynuclear leucocytes occur throughout the 

 proliferated connective tissue, especially in its superficial 

 portions immediately beneath the syncytium. 



Many of the uterine glands of the placental area, and 

 especially their peripheral portions, are now in process of 

 marked degenerative change. Various stages in the degenera- 



