306 HISTOLOGY. 



the decidua basalis degenerates and disappears, and the distal parts of 



(mm 



roV?f 





yncytium. 



Cuboidal cells of the 

 basal layer. 



Connective tissue. 



Blood vessel containing 

 nucleated red cor- 

 puscles. 



Oblique section of the epithelium. 

 FIG. 350. CROSS SECTION OF A HUMAN CHORIONIC VILLUS OF THE FOURTH WEEK OP PREGNANCY. 



the blood vessels in the tunica propria are destroyed. The uterine blood 

 escapes into the intervillous spaces, bounded by the syncytium, or where 

 this is deficient, by the basal cells. The maternal blood circulates in the 



Amnion. .. 



Chorion. 



Chorionic villi. 



Intervillous spaces. 



Attached villi. 



Muscularis. 



FIG. 351. DIAGRAM OF THE HUMAN PLACENTA AT THE CLOSE OF PREGNANCY. (Schaper.) 



intervillous spaces as shown in the diagram Fig. 351, and does not clot. 



