Uterine muscle 

 Remains of yolk sac 



Maternal blood 



sinus 

 Decidua basal is 



Placenta} septum 



Marginal sinus 



Fused decidua vera and 

 capsularis 



Chorion 

 Amnion 



FIG. 249. Section of the uterus, showing the relation of an advanced fetus to the placenta and mem- 

 branes (Ahlfeld). 



