244 



UROGENITAL SYSTEM 



wall of the decidua vera and d. basalis. 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. 237). The decidual cells are derived from the stroma 

 cells of the mucosa. They are large, being 50 /z in diameter, 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 occur the enlarged and tortuous uterine 

 glands of pregnancy (Fig. 237). During the first two months of pregnancy the 

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



Compact layer 



- Vein 



Cavernous layer s*-V* 



* Gland 



Vein 



Muscularis \ r 



FIG. 237. Vertical section through the wall of uterus about seven months pregnant with the membranes 



in situ (Schaper in Lewis-Stohr). X 30. 



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 endothelial 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- 

 pressed as the embryo grows (Fig. 234). To it is attached the chorion Iceve, the 



