264 THE DIGESTIVE SYSTEM 



Obstruction of the bile duct is followed by the absorption 

 of bile pigments into the blood, and they are deposited in 

 many of the tissues of the body and under the skin and 

 mucous membranes. When jaundice results from impaction of 

 a gall-stone in the bile duct or from inflammation of the mucous 

 membrane which lines the duct, its onset is sudden, and it is 

 not, as a rule, accompanied by any signs of obstruction to the 

 portal vein or the inferior vena cava. On the other hand, 

 when jaundice results from pressure due to extrinsic causes, 

 the condition is slow in its onset, increases steadily in degree 

 and is frequently associated with signs of venous obstruction. 



DEVELOPMENT OF THE LIVER AND BILIARY PASSAGES. At 

 a time when the stomach is scarcely discernible as a dilatation 

 on the primitive fore-gut (p. 249), the liver arises as a hollow 

 diverticulum from the ventral aspect of the gut immediately 

 caudal to the pylorus. This bud soon bifurcates into two 

 parts, one of which persists as a blind hollow sac and forms 

 the gall-bladder. The cells which line the other proliferate so 

 quickly that its lumen becomes obliterated and the solid mass 

 of cells invades the surrounding mesoderm, which forms the 

 fibrous framework of the liver. 



The NERVES OF THE LIVER AND BILE PASSAGES. Owing 

 to the proximity of the point of origin of the liver to the 

 stomach, it is not surprising to find that the sympathetic 

 nerves which supply the liver and bile passages arise from 

 segments of the spinal medulla (T. 7-9) in close relation to 

 the segments which supply the stomach (T. 5-8). In addition, 

 the liver receives branches from both vagi and a few twigs 

 from the right phrenic nerve which descend along the inferior 

 vena cava. 



It is well recognised that advanced pathological processes 

 may occur in the liver and yet give rise to no painful 

 symptoms. In this way, the liver closely resembles the lungs, 

 kidneys and pancreas, and it has already been pointed out 

 that these viscera contain very few unstriped muscle fibres 

 In solitary tropical abscess of the liver, the patient often 



