Histochemical observations on the pancreatic islets in normal and obese-hyperglycemic mice

Summary

In the islets of Langerhans in mice with the American variety of the obese-hyperglycemic syndrome (AO) and their thin litter mates (AN) the following observations were made:

• 1. In cryostat sections of fresh pancreatic tissue from AN-mice, both more centrally situated islet cells with yellowish white granules, and peripherally situated cells with brighter silver white granules were found with dark field microscopy. While the central cells were considerably degranulated in the AO-mice, the peripheral cells were also well filled with granules in these animals. The technique described offers, especially in the AO-mice, better possibilities of differentiation of the islet cells than with the granule staining methods of fixed pancreatic material, which are now generally used.

• 2. After intravenous injection of dithizone, abundant orange yellow zinc dithizonate granules were found in all islet cells with dark field microscopy of cryostat sections from fresh pancreatic tissue of AN-mice. By dissolving out these granules, the zinc content could be related to the different types of islet cells. It was possible in this way to show that the zinc in the islets of the AO-mice was mainly situated in the peripheral cells, containing the silver white granulation typical of untreated animals in dark field. The occurrence of a lower zinc content in the centrally situated islet cells in the AO-mice was also evident from the so-called “sulphide-silver method”.

• 3. A positive islet reaction to both acid and alkaline phosphatases was obtained in the AN-mice. The alkaline phosphatase activity was high in the peripheral parts of the islets of AN-mice, but much lower in the AO-mice. While the majority of islet capillaries were strongly positive as regards alkaline phosphatases in the AN-mice, in the AO-mice they were for the most part completely negative.

• 4. In spite of the existence of a prolonged hyperglycemia, no storage of glycogen could be demonstrated in the islets of the AO-mice. With fluorescence microscopy, the occurrence of masked lipids in the islets was observed in the AN-mice, and to an even higher degree in the AO-mice. On the other hand the sudanophilic reaction was negative throughout. The raised functional activity in the islet B-cells of the AO-mice was reflected in an enlargement and fragmentation of the Golgi apparatus.