THE ULTRASTRUCTURAL characteristics of the islet cells of the pancreas are sufficiently different to permit identification of cell types without recourse to the selective staining methods required for light microscopy.1-3 Such tinctorial methods often fail to indicate the cell type present in pancreatic tumors. This electron microscope study was undertaken to define the ultrastructural appearance of islet cell adenomas of different functional properties and to compare these tumor cells with the ultrastructural appearance of islet cells.
Materials and Methods
Biopsy specimens were obtained at surgery from two pancreatic tumors which exhibited the Zollinger-Ellison syndrome (recurrent peptic ulceration, gastric hypersecretion, and an adenoma of the pancreatic islets which does not produce insulin) and from the uninvolved parts of these pancreases. Specimens were also obtained from four tumors taken from patients who exhibited Whipple's triad (convulsions and coma accompanied by blood glucose levels of less than 50 mg% and relieved at