Discrepancies between histological and physical methods for trace element mapping in the rat brain.

This paper contains a comparison between four experimental methods for the detection of trace metals in biological tissues, e.g. autoradiography, dithizone-, Timm-staining and microPIXE (Particle Induced X-ray Emission). As research object the hippocampus of the rat was chosen and mainly the Zn-distribution in the fascia dentata has been examined. The comparison was judged on four criteria: spatial resolution, specificity, quantification and influence of the protein binding of the metal on the outcome of each method. Some additional Timm and microPIXE experiments have been performed to compare the metal concentrations for both normal and Zn-deficient rats. The Zn/Cu ratio for both kinds of rats were calculated and some striking differences in the concentrations were obtained. The Zn/Cu ratio for a normal rat was found to be about 40% higher than for a deficient one.