172 STUDENTS HISTOLOGY 



3. The central (or intralobular) veins, A, A (frequently 

 appearing as mere slits on account of the direction of the cut). 



The portal canals, G, G. (These are readily detected on account 

 of the deeply stained nuclei of the cells lining the hepatic ducts.) 

 (H.) 



5. Portal canals (too small for demonstration of the several 

 elements, but always distinguishable by the columnar epithelial 

 cells.) 



6. The larger portal canals, C. Note: (a} The large thin- 

 walled vein, D; (6) The duct, E; (c) The artery, F. 



7. The tortuous course of the hepatic cell-columns as com- 

 pared with the same in the section previously studied. 



8. The hepatic veins. (Observe their infrequency compared 

 with the sections of the portal veins. Note the small amount of 

 connective tissue around them greater, however, than that about 

 the central veins.) 



ELEMENTS OF A PORTAL CANAL FROM PREVIOUS SECTION 



OBSERVE: ( Fi g- Hi) 



(H.) 



1. The portal vein, V. (Note the nuclei of the few endothe- 

 lial cells remaining, and the corpuscular elements of the blood 

 in the lumen of the vein. Observe that the white corpuscles are 

 scanty, and deeply stained; also that many of the colored corpuscles 

 are granular, and show loss of pigment from action of the alcohol.) 



2. The hepatic artery, A. (In the human liver, the portal 

 canals frequently carry a number of arteries and ducts, instead of 

 one of each, as shown in the one selected for the illustration. The 

 arteries can nearly always be differentiated by the clear, wavy line 

 of the fenestrated membrane. Should the section have been in a 

 longitudinal direction with reference to the vessel, look for the 

 elongated nuclei of -the unstriated muscle-cells of the media, some 

 running with the artery the longitudinal and others at right 

 angles to its course the circular fibers.) 



3. The hepatic duct, D. (Observe the thickness of the wall, 

 depending, of course, upon the diameter of the duct itself, and the 

 presence of connective tissue supporting scattering unstriated 

 muscle-cells. Note the beautiful, clear, columnar cell-lining. 

 That these epithelial cells are polygonal in transverse section is 

 demonstrable at D, L, where the duct has been cut in a longitudinal 

 way, and the cells are seen from above. 



