LIVER. 



317 



mately unite to form the hepatic duct, which leaves the liver at 

 the transverse fissure. 



It is believed by some of the best authorities that the so-called 

 intralobular hile tubes or capillaries are mostly mere spaces 

 between the cells, the tubes being formed only at the periphety 

 of the lobule. 



The hepatic or hile duct (ductus cJioledochus) thus results 

 from the union of the branches of the hepatic tubes in the pos- 

 terior fissure of the liver. On leaving the liver, it passes between 

 the folds of the gastro-hepatic omentum, and reaches the walls of 

 the duodenum, where it meets with the principal duct from the 

 pancreas ; both these ducts, in the horse, enter the duodenum 

 together, some five icches 

 from the pylorus. In some 

 cases the two ducts have 

 been found to unite -before 

 reaching the wall of the 

 duodenum, thus forming a 

 short, single cr/aal, termed 

 the ductus communis. The 

 opening is guarded by a 

 prominent circular fold of 

 mucous membrane, the emi- 

 nence of Vater, which serves as a valve, preventing the entrance 

 of food from the duodenum. The ductus choledochus and larger 

 bile tubes consist of an external fibrous and slightly muscular 

 coat, and an internal mucous coat, lined with columnar epithelium, 

 and studded with numerous glands. 



The nerves come from the solar plexus, with branches from the 

 pneumogastric and diaphragmatic nerves. 



The blood of the portal vein, returned chiefly from the 

 abdominal alimentary canal, is charged with bile, which it i3 the 

 principal function of the liver to remove. This is achieved by 

 the vital power of the hepatic cells, while the blood is passing 

 through the intralobular capillaries. The blood- thuc doprived of 

 bile, passes into the intralobular veins, and so into the sublobular 

 and hepatic veins, while the bile gains the bile ti^ibes, and ulti- 

 mately the hepatic duct, to.be poured again into the intestine. 

 Bile is a greenish-yellow, viscid fluid, with an alkaline reaction ; 

 it is believed to stimulate peristaltic action, and the secretions 

 of the glands in the mucous membrane. 



Fig. 106. 

 Section shomng the manner in which the Bile and 

 Pancreatic Ducts enter the Intestine, a, Duct of 

 Wirsung ; b, Bile duct ; c, Union of the two ducts 

 on the eminence of Vater ; d, Valve ; e, Muscular 

 coat of duodenum ; /, mucous coat of ditto. 



