240 



THE UROGENITAL SYSTEM 



The basal plate, or compact layer of the decidua basalis, is composed of a con- 

 nective tissue stroma containing decidual cells, canaUzed fibrin, and persistmg 

 portions of the epithelium of the vilh. The canalized fibrin is beheved to be 

 formed both from the syncytial trophoderm of the vilh and from the modified 



■Svnr\liiim 



2).T — Ciiboiddl cells of the basal layer 



Connective tissue 



Blood vr^'^el containing 

 '^J ^ nuclcalcd red corpuscles 



Ohliqiir section of tlic epithelium 



Epilhdium' — 

 Epithelial nucleus ■-- 



Capillaries m^^ - - - - 



Syncytial knot 



Small artery - 



I — Syncytial knot 



•Epithelium 



Small vein 



• Capillary 



Syncytial knot 



Fig. 248. — Transverse sections of chorionic villi; A, at the fourth week; B, C, at the end of pregnancy 



(Schaper in Lewis and Stbhr). 



fibrin of the maternal blood (Fig. 242). From the basal plate, septa extend into 

 the intervillous spaces but do not unite with the chorion frondosum (Grosser in 

 Keibel and Mall,- vol. 1) . Near term these constitute the septa placenta which 

 incompletely divide the placenta into lobules, or cotyledons (Figs. 245 and 247). 



