i8o 



NORMAL HISTOLOGY. 



FIG. 224. 



The existence of a distinct independent wall to the bile-capillaries 

 has been the subject of much conflicting testimony; according to 



some, these vessels are with- 

 out distinct walls of their 

 own, while other authorities 

 regard the existence of a deli- 

 cate special wall consisting of 

 a homogeneous structureless 

 membrane as established. 

 The presence of a distinct 

 membranous wall seems ques- 

 tionable ; when it is recalled 

 that the bile-capillaries really 

 represent lumina of modi- 

 fied tubular glands, there 

 seems to be no greater neces- 



Section of rabbit's liver in which the bile-capillaries gjj-y f or or probability of the 

 () have been injected and appear as dark lines between . 



the ceils :c, blood-channels. existence of a membrane to 



limit the lumen of the bile- 

 tubule than in the case of other glands. The direct transforma- 

 tion of the secreting hepatic cells into the epithelium of the bile- 

 duct at the margin of the 



FIG. 225. lobule further opposes the 



assumption of such limiting 

 membrane, while examination 

 of livers in which the tubu- 

 lar type of the acini is re- 

 tained fails to show such 

 structures within the lumina 

 of the tubes. 



Emerging from the lobule 

 at the periphery to pass into 

 the adjacent interlobular con- 

 nective tissue, the small bile- 

 ducts empty into the larger 

 ones, which bear the branches 

 of the hepatic blood-vessels 

 company. The interlobular 

 bile-vessels gradually in- 

 crease in size, owing to the 



repeated union of the smaller tubes, until the larger trunks unite to 

 form the hepatic duct. While the walls of the smaller bile-ducts 

 consist of columnar epithelium strengthened by fibrous con- 

 nective tissue mixed with elastic fibres, those of the large vessels 



Section of liver of dog, including portion of lobule and 

 interlobular connective tissue (a) ; b, portal vein ; c, 

 hepatic artery ; d, bile-ducts ; e, small peripheral bile- 

 vessel ; g t blood-channels ; h, hepatic tissue. 



