278 HISTOLOGY 



garded as a special subdivision of the original diverticulum, rather than as 

 its expanded terminal portion. In certain mammals, as in the horse and 

 elephant, the gall bladder is lacking. After the hepatic duct has joined 

 the cystic duct, the common bile duct (ductus choledochus) thus formed 

 proceeds to the duodenum into which it opens, together with the pancreatic 

 duct, at the duodenal papilla. The common bile duct is an elongated 

 portion of the original hepatic diverticulum. 



Ligaments of the Liver. At the time of its earliest formation the liver 

 bulges laterally from the ventral mesentery, on both sides, thus forming 

 right and left lobes. The lobes are covered with the peritoneal epithelium. 



The mesenchyma beneath this epithelium pro- 

 duces loose connective tissue externally, and a 

 dense fibrous tissue, immediately surrounding 

 the trabeculae, internally; this latter becomes 

 the capsula fibrosa (or capsule of Glisson). 

 The part of the ventral mesentery extending 

 from the intestine to the liver is known as the 

 lesser omentum, and the part between the liver 

 and the ventral body wall is the falciform liga- 

 FIG 272.-THE LEFT SIDE OF AN ment. These lie in the median plane (Fig. 272). 

 nfnfeSf ' Beneath the liver, the peritoneal cavity comes 



d. c., Ductus choledochus; g. b., to extend across the median line so that the 



gall bladder; I. L, falciform 



bladder is covered with peritoneum, except 



d p 'iigame P nt7 a v. V c? i r.: along its attachment to the under side of the 

 liver. On the upper surface of the liver, the 



original broad connection with the septum transversum becomes rela- 

 tively narrow dorso-ventrally, and forms a pair of lateral ligaments which 

 pass from the upper surface of the liver to the diaphragm. They extend 

 across the liver at right angles with the falciform ligament and lesser 

 omentum. The left lateral ligament retains these simple relations and is 

 known as the left triangular ligament. The right lateral ligament, except 

 at its tip (the right triangular ligament} , extends down over the posterior 

 surface of the liver as an extensive area of fusion with the diaphragm; this 

 is the coronary ligament (Fig. 275). The significance of this asym- 

 metrical condition will be explained with the veins of the liver. 



Development of the veins of the liver. The hepatic trabeculae are always 

 in close relation with the veins which are conveying nutriment to the 

 heart. These are (i) the vitelline veins conveying nutriment from the 

 yolk-sac, (2) the umbilical veins conveying nutriment from the placenta, 

 and (3) the portal vein conveying absorbed food from the intestine. The 

 liver also has important relations with the vena cava inferior. 



The portal vein, which is the principal afferent vessel of the adult liver, is derived 

 from the vitelline veins. The latter; as they pass from the yolk-sac into the abdominal 



