Ultrastructural and functional changes in pancreatic acinar cells during autolysis

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Abstract
Effects of anoxemic cell injury on rat pancreatic acinar cells were studied in a preparation where tissue samples were incubated at temperature between 18-20.degree. C in a moist atmosphere for 0, 0.5, 1, 3, 6, 12 and 24 h in vitro. EM revealed that disintegration of acinar cells began by swelling of various cell compartments and gradual breakdown of cell membranes. Zymogen granules remained morphologically intact for at least 3 h. There were no signs of increased autophagic activity during the observation period. Myelin figures and other membranous remnants of disintegrated cells, together with individual cells and cell organelles whose morphology was relatively well preserved, were seen even after 24 h incubation. The secretory response of acinar cells to pancreozymin stimulation, as measured by amylase release into the incubation medium in vitro, decreased progressively closer to zero during 12 h autolysis. No active trypsin could be detected in tissue samples during the 24 h observation time. During hypoxic autolysis at room temperature between 18-20.degree. C in vitro: acinar cell disintegration resulted from breakdown of cellular membranes; autophagocytosis was not involved; most zymogen granules remained morphologically intact even at the time when cell membranes showed evidence of damage; there was no trypsin activation taking place in the tissue and acinar cells were capable of responding to secretory stimulation for 3-6 h after removal of tissue from the experimental animal.