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The epithelium of the main pancreatic duct is studied histologically and histochemically in mammals of different alimentary specialization. The features of the mucous epithelial barrier are found to be different depending on the type of digestion. The epithelium of carnivorous animals is glandular, but its secretion contains neutral glycoproteins as well. The mucous secretion produced by goblet cells and deep Nands of the duct in guinea pigs as well as in all herbivorous animals has a more protective action due to a high concentration of acid glycoproteins. Key Words: pancreas; duct; epithelium; barrier propertiesThe changes occurring in pancreatic ducts, which result from duodenopancreatic and biliopancreatic refluxes against the background of canalicular hypertension, play a key role in the development of acute and chronic pancreatitis [1,3]. The barrier properties of the duct epithelium are in such cases very seriously compromised. However, the structural basis for the resistance of the epithelium lining the pancreatic ducts has been insufficiently studied in experiment. There is no established relationship with the functional peculiarities of the digestive system that depend on the chief diet of animals.The cell composition and histochemical peculiarities of the mucous membrane epithelium of the main pancreatic duct (MPD) were studied here in common species of experimental animals.

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Regeneration of exo-and endocrine compartments of guinea pig and rat pancreas after partial resection is studied. The key role of [3-cell hypertrophy and acinoinsular transformation in the compensation of endocrine function and typical regeneratory modification in the exocrine pancreas are demonstrated. Key Words: pancreas; resection; regenerationDevelopment of surgical treatment of chronic pancreatitis and of organ-sparing operations for benign tumors of the pancreas [2] prompts further studies of the mechanisms responsible for the compensation of pancreatic function. Although regeneration of the exocrine pancreas was studied in sufficient detail [1,4,5], the problem of [3-cell recovery was not solved. Our aim was to study regeneration of the pancreatic islets after partial resection of the organ in comparison with our previous data obtained in experiments with ligation of the pancreatic duct [3]. MATERIALS AND METHODSRegeneratory changes occurring in the pancreas were studied in 46 guinea pigs and 18 albino rats of both sexes after resection of two thirds of the distal part of the pancreas. The animals were sacrificed 1, 5, 10, 20, 30, 60, and 90 days after surgery. Both surgery and sacrifice were performed under ether anesthesia. Pieces of the pancreas were fLxed in formalin, Rouget, Bouin, and Carnoy solutions and embedded in paraffin. Sections were stained with hematoxylin and eosin, iron hematoxylin, Mallory phosphotungsDepartment of Histology, Medical University, Kursk; Department of Biology, Russian Medical University, Moscow tic acid hematoxylin, aldehyde fuchsin, and Fenaf stain. Some pieces of rat pancreas were fixed with osmium tetroxide and embedded in Epon-Araldite. Semithin sections were stained with toluidine blue. Ultrastructure of rat pancreas was studied by transmission electron microscopy under a UEMB-100K electron microscope. Ultrathin sections were cut in an LKB-8800 ultratome and contrasted with uranyl acetate and lead citrate by the method of Reynolds. Morphometric data on the guinea pig pancreas were analyzed by the variation statistics methods using Student's t test and elements of the information theory [31. RESULTSChanges in the exocrine pancreas after resection were typical in both species and occurred at the same interval as after ligation of the pancreatic ducts [3]. Some specific changes were observed in pancreatic islets. Acinal hypertrophy and more intense staining of homogeneous and zymogenous zones of the exocrine pancreas after resection reflected impaired secretion. Hyperplasia of the goblet cells and the glands of the large ducts similar to that occurring after ligation of pancreatic ducts was observed in guinea pigs. After resection, an increase in mitotic activity of ductal epithelium was recorded earlier