236 



THE UROGENITAL SYSTEM 



wall of the decidua vera and d. basalts. The compact layer is much thicker than 

 the spongy layer and in it are found numerous stroma cells, enlarged blood vessels, 

 and decidual cells (Fig. 244). The decidual cells, frequently multinucleate, are 

 derived from the stroma cells of the mucosa. They are large, being 50 /i in di- 

 ameter, with clear cytoplasm and vesicular nuclei. Their function is in doubt. 

 Glycogen has been found in them, but during the later months of pregnancy many 

 of them degenerate. 



In "the spongy layer of the mucosa cfccur the enlarged and tortuous uterine 

 glands of pregnancy (Fig. 244). During the first two months of pregnancy the 



Compact layer* 



■Vein 



— Gland 



Spongy layer 



'^^-Vein 



Muscidarisi 



Fig. 244. — Vertical section through the wall of the uterus about seven months pregnant with the mem- 

 branes in situ (Schaper in Lewis and Stohr). X 30. 



long axes of the glands are perpfendicular to the surface of the mucosa. Later, as 

 the decidua is stretched and compressed owing to the growth of the fetus, the 

 glands are broadened and shortened and the cavities of the glands become 

 elongated clefts parallel to each other and to the surface of the decidua. The 

 gland cells become stretched and flattened until they resemble endothehal cells. 

 At birth, or in case of late abortion, the plane of separation is in the spongy layer. 

 Only the deep portions of the glands remain attached to the uterine wall, and, by 

 the division of their cells, regenerate the epithelium of the uterus. 



The Decidua Capsularis. — The capsularis, as we have seen, becomes com- 



