420 



THE DIGESTIVE SYSTEM 



Nerves. The nerves of the liver are mostly of the non-medullated 

 variety. They follow the portal canals and are distributed to the walls 

 of the blood-vessels, the walls of the bile ducts, and to the capsule of the 

 liver. Naked fibrils from these trunks also enter the lobules and form 



a plexus among the hepatic cells (Korolkow, 

 Anat. Anz., 1893), in relation with which they 

 form fine terminal brushes and varicose end 

 knobs (Berkley, Johns Hop. Hosp. Eep., 1895). 

 The liver secretes the bile a fluid which aids 

 in the digestion and absorption of fats and in 

 fact probably serves also an excretory role. Bile 

 has a greenish-yellow color, due in part to the 

 presence of the pigment bilirubin, which is be- 

 lieved to be identical with the hematoidin elab- 

 orated from the hemoglobin of the erythroplas- 



^ ( ] s disintegrating in the spleen, and carried to 



. . 



the hver by way ot the splenic and portal veins. 



Under certain pathological conditions known as 

 jaundice, bile finds its way within the liver di- 

 rectly into the blood stream where it produces hemolysis of the red 

 corpuscles. In addition to its bile-producing activity, the liver functions 

 also as an organ of internal secretion, in the conversion of glycogen into 

 sugar and the elaboration of urea. Experimental evidence indicates that 

 the liver is concerned greatly also with the production of fibrinogen 

 (Whipple, Amer. Jour. Physiol., 1914). 



FIG. 394. INTRALOB- 

 ULAR NERVE FIBERS 

 IN A RABBIT'S LIVER. 



a, hepatic cells; b, 

 nerve fiber. Golgi stain. 

 Highly magnified. (Af- 

 ter Berkley.) 



THE GALL-BLADDER 



The wall of the gall-bladder consists of three coats: (1) mucous; 

 (2) muscular; (3) fibroserous. The mucous membrane is markedly 

 folded or corrugated, the irregularly polygonal depressions being rela- 

 tively broad at the fundus but becoming narrower toward the neck of the 

 organ. The lining epithelium is of the tall columnar variety, with 

 spheroidal or ovoid nuclei which lie near the base of the cell. The free 

 extremity of the epithelial cells presents an indistinct cuticular border. 

 The epithelium follows all the folds of the mucosa and lines the inter- 

 vening depressions. 



The corium of the mucosa consists of delicate connective tissue and 

 contains a few smooth muscle fibers derived from the muscular coat. 



