MORPHOLOGY OF THE PANCREATIC DUCT SYSTEM IN MAMMALS

The morphology of pancreatic excretory duct segments was reviewed in m ammals. The fine structure of the epithelial lining was described in i ntercalated ducts, intra- and extralobular ducts, and in major pancrea tic ducts. Morphological characteristics of the various cell types com prising to the duct epithelium were detailed. Principal cells in the e pithelial linings of interlobular and major pancreatic ducts (''Wirsun giocytes'') were discussed with respect to their appearance as either clear or dark variety. In addition, the capacity of both these cell ty pes in elaborating mucoid glycoprotein secretions was considered and i ntra- and extraepithelial mucoid glands of major pancreatic ducts (duc tular glands, accessory glands) was described. Finally, the wall compo sition of the various excretory duct segments was described. The prese nce of smooth muscle cells, myofibroblasts, and a peculiar periductal vascular plexus in major interlobular ducts and in main pancreatic duc ts was emphasized. (C) 1997 Wiley-Liss, Inc.