RESUMO
The objective of this study was to analyze the morpho-functional remodeling of the epitheliocytes of stomach fundic glands in Siberian chipmunk under different seasonal conditions. The methods of light and electron microscopy were used. It was shown that during summer period, the structure of gastric fundic mucosa of Siberian chipmunk was similar to that one in other mammals. In contrast, in winter, during the periods of hypothermia, the cells of the fundic glands in the gastric corpus demonstrated the changes indicative of the suppression of their secretory activity. During the spontaneous arousals, all the elements of the gastric glands were activated, while the animals consumed the stored food. The present results were compared with the materials obtained earlier in the study of ground squirrels which also have a period of winter hibernation. Gastric cell remodeling in chipmunks during hypothermia was comparable in its trend with the changes taking place in ground squirrels, however, these changes were more pronounced in the latter. Food digestion in the stomach of chipmunk took place not only during the periods of normothermia, but also in the course of slow decline of the body temperature, when animals fell into a state of torpidity, and it recommenced at the early stages of animal rewarming during frequent episodes of its spontaneous arousal. Differences in the changes found in chipmunks and ground squirrels are associated with ecological peculiarities of these species and in the characteristics of the adaptation during the winter period.