Ultrastructure of the stomach of the small short-tailed shrew, Blarina brevicauda c.
The normal gastric ultrastructure has been characterized for the small short-tailed shrew, Blarina brevicauda c., which is a primitive eutherian and one of the smallest living mammals with extraordinarily high metabolic rate. In general the cell types present and cytologic character of gastric mucosal, submucosal, and muscularis cells were similar to that reported for other more advanced small mammalian species. Chief cells, endocrine cells, and lamina proprial elements were morphologically identical to their counterpart in rats, ferrets and other small carnivores. Distinctive cytologic features in this species of shrew included the scanty monolayer or small number of mucous granules in the simple columnar surface epithelial cells of the mucosa, and the thin elongated shape of their microvilli. Dense bodies were absent in the parietal cell mitochondria of the shrew, though usually abundant in other mammalian parietal cells. Our data indicate few morphologic specializations in the shrew stomach which can be correlated with their high rate of food assimilation and metabolic demands, though future studies of mucosal biochemistry and lower gut morphology may reveal such adaptations.