192 MANUAL OF HISTOLOGY. 



with numerous irregular excavations, measuring 0.15 0.3 mm. 

 in their long diameter. In this trunk there occur also a great 

 number of pores or orifices, which, on examination, prove to 

 be the mouths of the passages leading from simple and com- 

 pound gland -like bodies, the so-called glands of the bile-ducts. 

 The simple glands consist merely of single vesicles, or alveoli, 

 with afferent passages, all of which are imbedded in the mu- 

 cous membrane ; or of two or more vesicles with a single pas- 

 sage. The compound glands are formed by the union of two 

 or more simple ones, which have a common passage. The}^ are 

 quite large, and their expanded portions lie on the outer sur- 

 face of the hepatic duct. When filled by injection with gela- 

 tine they are visible to the naked eye. The passages pierce 

 the walls of the duct at an acute angle, pursuing a course 

 within its walls, nearly parallel to the duct itself ; the opening 

 into the mucous membrane is therefore quite a distance from 

 the gland-vesicles. According to Henle, these compound glands 

 are not found in the larger branches of the hepatic duct, but 

 they occur frequently in the network of bile-ducts situated 

 in the transverse fissure. Allusion has already been made to 

 them. The vesicles measure 0.04 mm. in diameter, and, like the 

 excavations in the larger branches of the duct, are lined with a 

 cylindrical epithelium, in no way differing from that of the 

 duct itself ; the afferent passages also possess the same kind 

 of epithelium. 



Structures allied to these excavations and glands occur in 

 small number, in the bile-ducts ' which are found in the liga- 

 mentum triangulare and on the diaphragm, where they appear- 

 as villous prominences on the duct- walls. 



According to Theile, Weber, and others, these bile-ducts represent the last 

 vestiges of an atrophied liver substance, the existence of which dates back to 

 infancy, or perhaps to fetal life. 



The excavations in the larger branches are either simple 

 diverticula of the internal walls, or the openings of lateral bile- 

 ducts ; the punctate pores are the orifices of the outlet pas- 

 sages of duct-glands. 



Capillary bile-ducts. When the larger bile -ducts, by con- 



1 Vasa aberrantia of E. H. Weber. 



