3 o8 



HISTOLOGY. 



The maternal arteries are in the septa but the veins are in the spaces 

 between them. 



Chorionic villus. 



Blood vessel. 

 k- - Red corpuscles. 



W" Connective tissue. 

 Syncytium. 



__ Hyalin. 



Deep layer of chori- 

 onic epithelium. 



Connective tissue. 

 Leucocytes. 



&.' <* *. '" 



" 



f * r ^f '. ^<5y *il 



?.< r7 * 4 -. V; .-*'< 



C v _ , v " 



Homogeneous layer. 

 Amniotic epithelium. 



FIG. 353. FROM A CROSS-SECTION OP A MATURE HUMAN PLACENTA. X 260. 



UMBILICAL CORD. 



The umbilical cord is a translucent glistening white or pearly rope 

 of tissue about two feet in length, extending from the umbilicus to the 

 placenta. It consists of mucous tissue (p. 37) covered with epithelium 

 and containing at birth three large blood vessels, two arteries and a vein 

 (Fig. 355, B). The parallel arteries generally wind around the vein 

 making sometimes forty revolutions. The surface of the cord shows 

 corresponding spiral markings and often irregular protuberances called 



