118 



CHOLINE 



to such large vessels is analogous to that of houses at the edge of a highway 

 which must be approached cirbuitously l)y way of secondary sideroads and 

 streets. To reach such a house, the traveler would have to traverse as great 

 a distance after leaving the highway as if the building were not located 

 near any main route at all. In the liver, parenchymal cells beside large 

 conducting portal veins (in contrast to cells around terminal, distributing 



Fig. 16. Similar preparation to that shown in Fig. 15. A portion of a large conduct- 

 ing branch of the portal vein occupies the center of the field and is surrounded by 

 fibrosis (clear area) . Branches from this extend toward the small trees of intact sinu- 

 soids in which terminal branches of the portal vein link with the sinusoids and are 

 free of encircling trabeculae (upper left corner) . Although there is periportal fibrosis 

 around the large portal venous branches, the small distributing portal venules are 

 not directly involved and from a functional standjjoint the distribution of the tra- 

 beculae is non-portal. 



venules) are no more periportal in a physiological sense than cells in other, 

 more obvious, non-portal regions. Cells adjacent to non-terminal portal 

 canals are therefore periportal only in a limited regional sense. In terms of 

 blood supply, with reference to the entry of blood into a parenchymal unit, 

 these portions of the parenchyma are non-portal, since to reach them blood 

 must first traverse sinusoids for some distance. Lesions, such as fibrosis 

 around conducting portal triads, are therefore periportal in a geographical 

 sense only. To be periportal from a functional standpoint, the lesions should 

 involve parenchymal cells adjacent to the proximal end of the sinusoidal 



