The exocrine pancreas in patients with hyperinsulinemic hypoglycemia. A morphometrical and ultrastructural study.

The exocrine pancreas has been studied morphometrically and ultrastructurally in 12 patients with insulin-producing tumors in comparison with control patients free from gastrointestinal or pancreatic diseases and with normal glucose homeostasis. Light microscopical examination and morphometrical data revealed that in the insulinoma-bearing patients acinar cells undergo a marked and significant decrease in zymogen granule content, together with a slight reduction in the mean cell area. Such changes were accompanied by ultrastructural features indicating increased production and exocytosis of zymogen granules. The findings concerning centroacinar/ductular cells are consistent with an increase in their number and mean cell area, and an enhancement of their functional activity. In synthesis, both the enzyme- and bicarbonate-secreting cells appear to be greatly stimulated in conditions of chronic hyperinsulinemic hypoglycemia owing to the presence of insulinomas.