

Fig. 22. The relation of die fetal to 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 rilled 

 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 and Co. 



