Abstract
Rabbits and rats were given single injections of aurothiomalate by different routes. The animals were killed at progressive intervals, and sections from various organs were examined by electron microscopic x-ray microanalysis. Ultrastructurally, characteristic material was regularly found in vacuoles, dense and heterogeneous bodies of macrophages, hepatocytes and renal epithelial cells. Occasionally, other mesenchymal cells also contained gold. Histochemical and analytical tests showed that the gold-containing organelles were devoid of acid phosphatase activity. The generalized rapid spread, retention and selectivity of localization after a single small dose make aurothiomalate a useful marker substance for ultrastructural studies.