Distribution of heavy metals and their ultrahistochemical determination in the organs of calves

Abstract

The distribution of Cd, Zn, Se and Cu in the tissues of animals receiving different total doses of these metals for different time periods was studied at the submicroscopical level. In experiment I, 32 calves of both sexes were given heavy metals singly (Cd and Zn) or in combination (Cd, Zn; Cd, Se) from 2 to 14 weeks of age. Experiment II included 21 bulls which received Cd, or Cd and Cu or Cd and Zn in a diet from 3 to 15 months of age. For ultrahistochemical examination, samples of liver, kidney, pancreas, testis or ovary and diaphragm were collected in experiment I and those of liver, kidney, pancreas and testis in experiment II. The ultrahistochemical method used was based on the detection of metal sulphides using a hydroquinone developer with silver nitrate added. The foci of reduced silver on sulphide molecules were identified as dark granules in cell cross-sections. In experiment I, after combined administration of Cd and Zn, the highest amounts of reduced silver granules were seen in the cytoplasm of hepatocytes and cells of the proximal and distal renal tubules and the lowest amounts were found in glandular cells of the pancreas. Administration of Cd and Se resulted in the presence of large numbers of granules in the nuclei and nucleoli of spermatogonies. In experiment II, ingestion of Cd and Zn in feed led to the appearance of highest amounts of granules in the nucleoli, nuclei and cytoplasm of cells in testes, kidneys and pancreas. Following Cd intake, the highest accumulation of granules was observed in the nucleoli of hepatocytes and cells of the proximal and distal renal tubules. Combined Cd and Cu produced the highest numbers of granules in cells of the proximal and distal renal tubules and in the nucleoli and nuclei of germinal epithelium.