SECT. 1 6 1.] GALL-BLADDER AND BILE-DUCTS. 349 



membrane and a fibrous layer, which latter also contains a few 

 muscular fibre-cells, though, upon the whole, so sparingly, that these 

 duets cannot be said to possess a special muscular coat. 



The gall-bladder possesses a delicate muscular coat, between the 

 peritoneal covering and the abundant submucous tissue, whose 

 fibre-cells, 003'" to o'O^" long, run chiefly in the longitudinal and 

 transverse direction, and have only indistinct nuclei. The mucous 

 membrane is characterised by numerous larger and smaller reti- 

 culated folds, in which there exists a capillary network entirely 

 similar to that of the broad intestinal villi. It is covered with 

 a cylindrical epithelium, whose separate cells, like the coats of 

 the bladder in general, are often tinged with bile, and do not 

 always present distinct nuclei. 



The biliary ducts contain in their walls a number of small, race- 

 mosc, yellowish mucous glands, gall-duct-glands, as they are termed, 

 whose glandular vesicles, o - oi6'" to o'024'" in size, do not essen- 

 tially deviate from those of other small racemose glands. In the 

 ductus hepaticus, choledochus, and the low T er part of the cysticus, 

 the glands are very numerous in, and in part external to, the 

 fibrous coat, of \"' to 1" and more in size, and open singly or 

 several together, by mouths of o - i" to O'l/^" in diameter, which 

 are visible to the naked eye, and give the mucous membrane of 

 these canals a reticulate appearance. At the commencement of 

 the cystic-duct the glands are rare, and are, in any case, not constant 

 in the gall-bladder, in which some believe they have seen them. 

 On the other hand, glands are seen in the branches of the ductus 

 hepaticus as far as those of \'" in diameter, and open in part with 

 two rows of minute openings, visible in these ducts. 



Wo have still to notice here some peculiar ramifications of tlie bile-ducts, 

 the vasa aberrantia (E. II. Weber). They are met with — in the ligamentum 

 trin Hi/ id are sinistrum, in the membranous pons, which connects the Spigelian 

 and right lobes behind the vena cava, then in the membranous pons which 

 often covers the vena umbilicalis, in the large portal canals (Bade), and at 

 the border of the fossa of the gall-bladder — as canals, 0-006'" to o'ozj"' wide, 

 and consisting of a fibrous coat and small cells. In the fossa transversa 

 hepatis, the right and left branch of the ductus hepaticus (and its smaller 

 branches in this situation), give off, according to E. II. Welter, a number of 

 finer twigs, which spread out in the connective tissue of the capsule of 

 Glisson covering the fossa, and form a network, which thus connects the right 

 and left hepatic duct. Many smaller branches of these gall-ducts terminate 

 with short swollen extremities, , 2 l'" to T ' s '" in diameter ; and upon the walls of 

 these ducts, in general, there exist a number of roundish projections, which, 

 like the walls of the smallest bronchial ramifications, appear to be formed by 

 flattened, coalesced vesicles having wide communications with the cavity of 



