Proportions of various endocrine cells in the pancreatic islets of wood mice (Apodemus speciosus)

Using wood mice (Apodemus speciosus) captured in the wild in Niigata, we an alysed the proportion of various endocrine cells in pancreatic islets for b oth immunohistochemical and microscopic characteristics. In both the dorsal and ventral portions of the pancreas, the centre of the pancreatic islets was occupied predominantly by insulin-positive (B) cells, surrounded by glu cagon-positive (A), somatostatin-positive (D), and pancreatic-polypeptide-p ositive (PP) cells. Although the proportions of the various endocrine cells in pancreatic islets varied from one mouse to the next, in most animals B cells accounted for more than half of all endocrine cells. Dorsal and ventr al portions of the pancreas differed in the proportions of various endocrin e cells, specifically, in the A-to-PP cell ratio: the proportion of PP cell s was higher in the ventral portion. The same tendency is seen in humans, r ats and mice. Microscopic examinations revealed morphologically distinct se cretory granules in A, B and D cells. The morphology of these granules was similar that of secretory granules found in rats and mice.