ANATOMY OF THE EXCRETORY BILIARY PASSAGES. 397 



known that there are either canals or interspaces between the liver-cells in 

 the lobules, and that these open into the interlobular hepatic ducts. It is 

 still a question, however, whether these passages be simple spaces between 

 the cells or true vessels lined with a membrane. 



Anatomy of the Excretory Biliary Passages. Between the lobules the 

 ducts are very small, the smallest measuring about yj-g- of an inch (8 ft) in 

 diameter. They are composed of a delicate membrane lined with epithe- 

 lium. The ducts larger than T ^nr f an i ncn (about 20 ft) have a fibrous 

 coat, formed of inelastic with a few elastic elements, and in the larger ducts, 

 there are, in addition, a few non-striated muscular fibres. The epithelium 

 lining these ducts is of the columnar variety, the cells gradually undergoing 

 a transition from the pavement-form as the ducts increase in size. In the 

 largest ducts there is a distinct mucous membrane with mucous glands. 



Throughout the extent of the biliary passages, from the interlobular canals 

 to the ductus choledochus, are little utricular or racemose glands, varying in 

 size in different portions of the liver. These are situated, at short intervals, 

 by the sides of the canals. The glands connected with the smallest ducts are 

 simple follicles, -g-j-g- to ^j-g- of an inch (31 to 62 ft) long. The larger glands 

 are formed of groups of these follicles, and they measure -^^ or y-J-g- of an 

 inch (100 or 250 ft) in diameter. The glands are only found connected with 

 the ducts ramify- 

 ing in the sab- 

 stance of the liver, 

 and they do not ex- 

 ist in the hepatic, 

 cystic and common 

 ducts. They are 

 composed of a ho- 

 mogeneous mem- 

 brane, lined with 

 small, pale cells of 

 epithelium. If the 

 ducts in the sub- 

 stance of the liver 

 be isolated, they are 

 found covered with 

 these little groups 

 of follicles and have 

 the appearance of 

 an ordinary race- 

 mose gland, except 

 that the acini are 

 relatively small and scattered. This appearance is represented in Fig. 134. 



The excretory biliary ducts, from the interlobular vessels to the point of 

 emergence of the hepatic duct, present frequent anastomoses with each other 

 in their course. 

 27 



FIG. 134. Racemose glands attached to the biliary ducts of the pig ; mag- 

 nified 18 diameters (Sappey). 



1,1, branch of an hepatic duct, with the surface almost entirely covered 

 with racemose glands opening into its cavity ; 2, branch in which the 

 glands are smaller and less abundant : 3, 3, 3, branches of the duct with 

 still simpler glands ; 4, 4, 4, 4, biliary ducts with simple follicles at- 

 tached ; 5, 5, 5, 5, the same, with fewer follicles ; 6, 6, 6, 6, 6, anasto- 

 moses in arches ; 7, 7, 7, angular anastomoses ; 8, 8, 8, 8, anastomoses 

 by transverse branches. 



