Applications of autometallography to heavy metal toxicology.

Application of autometallography (AMG) to histological material from humans and animals exposed to gold, silver and mercury has made it possible to localize these heavy metals at light and electron microscopic levels. Because of high sensitivity of the technique, traces of the three metals have been demonstrated in tissues and cells that had previously not been suspected of containing metals. A chelatable pool of zinc in the synaptic vesicles of the zinc-positive neurones can be demonstrated by AMG in the brain. The well defined staining pattern can be used to estimate volumes of cortical subdivisions. Volumetric studies based on autometallographic differentiation of cortical regions have provided valuable information about the effects of different toxicants. AMG can be combined with new quantitative methods, such as electron energy loss spectroscopy (EELS), electron probe X-ray microanalysis (EPMA) and laser microprobe mass analysis (LAMMA), to enhance detection of AMG metal catalysts with these techniques.