ULTRASTRUCTURES OF ATYPICAL ACINAR CELL NODULES IN RAT PANCREAS INDUCED BY 4-HYDROXYAMINOQUINOLINE-1-OXIDE

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  • 1 January 1976
    • journal article
    • research article
    • Vol. 34  (5) , 501-509
Abstract
A single i.v. injection of 4-hydroxyaminoquinoline-1-oxide (4HAQO) to rats induced multiple atypical acinar cell nodules in the pancreas. Ultrastructure of cells in these nodules was examined at 6, 9 and 12 mo., and the features were compared to those of developing embryonal pancreas. The cells in the nodules were exocrine acinar cells in type and exhibited several features which distinguished them from the nonnodular acinar cells. Irregular nuclear shape with enlarged nucleoli was frequently observed. Zymogen granules in the nodular cells appeared as vesicles with contents of extreme electron lucency and their ultrastructural appearance was similar to those of developing embryonic pancreatic acinar cells at 16 and 18 days of gestation. At the cell periphery, the lateral cell membrane showed bizarre interdigitation and the ectoplasm showed hyalonplasmic rarefaction. The acinar cell nodules induced by 4-hydroxyaminoquinoline-1-oxide were probably composed of a new population of phenotypically altered acinar cells showing nuclear abnormalities, modified cell to cell interaction and a possible defect in synthesis and/or maturation of secretory enzymes. The latter may indicate an arrest in the differentiation of acinar cells. The significance of these findings was discussed and it was suggested that the atypical nodules in the pancreas induced by 4-hydroxyaminoquinoline-1-oxide may represent early neoplastic foci.