Effects of intravenously administered tetra-thiomolybdate on the distribution of copper in the liver and kidney of copper loaded sheep: a histochemical study.

The effects of intravenously administered thiomolybdate on the liver and kidney of copper loaded sheep were studied using 16 ewes in three groups. Copper, iron and molybdenum concentrations were determined by spectrophotometry and the distribution of copper in the liver and kidney was studied histochemically. Following thiomolybdate administration, the concentration of copper in the liver was reduced, that of molybdenum increased and the concentration of copper and molybdenum in the kidney increased. The reduction of copper concentration in the liver was associated with reductions in the number and size of granules in hepatocytes which stained positively for copper and in the number of Kupffer cells containing positively staining granules. The decrease in the amount of copper in hepatocytes appeared to be greater than that in Kupffer cells. This effect was greatest in the centrilobular zones and least in the periportal zones. The increased concentration of copper and molybdenum in kidney was associated with an increase in the number and size of granules staining positively for copper in the epithelial cells of the proximal convoluted tubules which suggested an uptake of copper-molybdenum complexes by the lysosomes of these cells.