Zinc mapping and density imaging of rabbit pancreas endocrine tissue sections using nuclear microscopy

Nuclear microscopy is a suite of techniques based on a focused beam of MeV protons. These techniques have the unique ability to image density and structural variations in relatively thick tissue sections, map trace elements at the cellular level to the microgram per gram (dry weight) level, and extract quantitative information on these elements. The trace elemental studies can be carried out on unstained freeze-dried tissue sections, thereby minimizing any problems of contamination or redistribution of elements during conventional staining and fixing procedures. The pancreas is a gland with different specialized cells and a complex hormonal activity where trace elements play an important role. For example, zinc has an active role in insulin production, and calcium ions participate in the stimulation and secretion process of insulin. Using nuclear microscopy with a spatial resolution of 1 mum, we have located, using zinc mapping, the islets of Langerhans in freeze-dried normal rabbit tissue sections. The islets of Langerhans contain beta-cells responsible for insulin production. Subsequent quantitative analyses have indicated elevations in most elements within the islets of Langerhans, and significantly so for the concentrations of Zn [3,300 compared to 90 microg/g (dry weight)] and Ca [1,100 compared to 390 microg/g (dry weight)].