[Electron microscopical investigations on islets of Langerhans in sand rats (Psammomys obesus) before manifestation of diabetes mellitus (author's transl)].

Electron microscopical investigations of islets of Langerhans are carried out in "protodiabetic" sand rats. In the B-cells and beta-Granules (2 to 5) aggregated. Mitochondrias, Golgi apparatus and rough endoplasmic reticulum are increased. These B-cells are stimulated. The A-cells are degranulated, and lipofuscin-granules are in the cytoplasm present. These cells were stimulated too. The D-cells are not stimulated.