Ultrastructural characterization of peninsular pancreatic acinar cells in the hibernating dormouse Muscardinus Avellanarius

Abstract

In a previous study we analysed the exocrine pancreas of the hazel dormouse Muscardinus avellanarius, demonstrating several structural modifications of teleinsular acinar cells (located at a dis tance from the Langerhans islets) during the hibernating cycle. In the present study, we investigated the peninsular acinar cells (closely surrounding the Langerhans islets) of the same dor mouse, by combining morphological, morphometrical, and im munocytochemical analyses. Our observations demonstrate that, during hibernation, several cytoplasmic organelles undergo struc tural modifications; cells, nuclei and zymogen granules decrease in size, and α‐amylase content falls; however, upon arousal, all euthermic features are restored. All these data are consistent with a marked reduction in metabolic activities (especially protein syn thesis and secretion) during hibernation, and their resumption up on arousal. Moreover, when changes of peninsular cells are com pared with those of teleinsular cells, it is evident that peninsular cell structural constituents are more affected by the functional rest during hibernation. This is probably related to the paracrine ac tion of the islet hormones on the surrounding acinar cells.