Histological and histochemical investigations on the Langerhans' islets of the frog (Rana ridibunda).

The Langerhans' islets of the frog Rana ridibunda are built up of A, B, and D cells like other vertebrates. The phospholipids (Baker's test) are located in the capillary pole of the B-Cells, where also beta-granules are present. In the cells of the endocrine pancreas there is found also some quantity of glycogen, but the reaction for zink is negative. The quantity of RNA in the cytoplasme of the islet's cells is minimum.