222 



HISTOLOGY. 



lesser omentum, the umbilical vein is on the left of the gall bladder from 

 which it is separated by the quadrate lobe. After the umbilical cord is 

 severed the vein becomes a fibrous strand, known as the round ligament of 

 the liver, Fig. 249, r .1. It extends from the umbilicus along the free margin 

 of the falciform ligament, and under the liver to the lesser omentum. From 

 this point to the vena cava the umbilical vein is called the ductus venosus. 

 It follows the hepatic attachment of the lesser omentum, and there it forms 

 after birth, the ligament of the ductus venosus. 



Development of the connective tissue and hepatic artery. The history 

 of the liver has been described to that point where it consists of a great net- 

 work of entodermal trabeculae connected with the intestine by a single 



Branch of portal vein. 



Large interlobular bile duct. 



Interlobular connective 

 tissue. 



Central veins. 



FIG. 250. FROM A TANGENTIAL SECTION OP THE HUMAN LIVER. X 40. 



The three central veins in cross section mark the centers of three lobules, which are not sharply separated 

 at the periphery from their neighbors. Below and at the right the lobules are cut obliquely and 

 their boundaries are not. 



duct. Its trabeculae are separated by a very small amount of connective 

 tissue from the endothelium of the sinusoids. The latter are essentially 

 subdivisions of the portal vein which reunite in the vena cava inferior. 

 Later in development the connective tissue around the principal branches 

 of the portal vein increases so as to be conspicuous; to a less extent that 

 which surrounds the main hepatic branches of the vena cava is also in 

 creased. Since the portal branches are associated with the bile ducts they 

 may be distinguished from the caval branches. Moreover the hepatic 

 artery which develops rather late, grows into the connective tissue along 

 the bile ducts. It supplies the fibrous capsule and the connective tissue 

 layers with capillaries, which empty into the adjacent sinusoids and into 

 the portal capillaries limited to the connective tissue. Thus there is a 



