FIG. 22. THE RELATION OF THE FETAL TO THE MATERNAL 

 BLOOD IN THE PLACENTA 



Arrows indicate the supply and exhaust of the maternal blood in the 



large intervillous spaces. 



a, sinus of uterine vein; b, muscle tissue of uterine wall; c, uterine vein; d, 

 uterine artery; e, sinus of uterine vein; f, decidua basalis; g, uterine artery; h, 

 intervillous space filled with maternal blood; i, syncytium; j, villus; k, umbilical 

 vein (fetal) ; 1, umbilical artery (fetal) ; m, uterine artery. 

 From Prentiss and Arey, Embryology. 

 By permission of W. B. Saunders & Co. 



