Morphometric analysis of the pancreas regenerating after resection

Abstract

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