The lysosomal system of the two types of synoviocytes (A and S) from the knee joint of normal rat synovial membrane was studied by electron-microscopic acid phosphatase cytochemistry. In random sections of the synovial intima lysosomes were more often encountered in the A-cell profiles than in the S-cell profiles. Characteristically, type-A synoviocytes showed many large and medium-sized lysosomes the cytochemical appearance of which varied considerably. No acid phosphatase activity was detectable in the cisternae of the Golgi apparatus or in the Golgi vesicles. In type-S synoviocytes the lysosomes were smaller, and more uniform in cytochemical appearance. Heavy deposits of acid phosphatase reaction product were constantly demonstrated in cisternae of the Golgi apparatus as well as in smooth-walled Golgi vesicles in type-S cells. The findings that type-A and type-S synoviocytes show distinctly different organization of the lysosomal system indicate that the roles of the lysosomes in these two types of cells may be different.

SUMMARY The concentrations of gold in erythrocytes, whole blood, cell-rich plasma, and cell-free plasma were investigated in 17 patients with rheumatoid arthritis undergoing long-term chrysotherapy. Gold estimations were performed with a graphite tube atomic absorption spectrophotometer. Significant quantities of gold were found in isolated erythrocytes of 12 patients. There was no correlation between erythrocyte gold and therapeutic response, plasma gold, and gold in whole blood. Nor did gold in whole blood or plasma show any correlation with therapeutic response and toxic reaction. However, all patients (3) with toxic reactions had a significantly higher gold concentration in the erythrocytes than the patients without toxic reactions. This result indicates that erythrocyte gold estimations could provide a useful warning of impending toxic reactions.

A histochemical technique which permits the simultaneous visualization of heavy metals and acid phosphatase at the ultrastructural level is described. The technique was applied to the anterior pituitary gland, the spinal cord and the liver. In all of the tested organs, both mercury and silver were found to accumulate primarily in the lysosomes, although small amounts of both metals could be observed in other organelles including endocytotic vesicles. In the anterior pituitary, few mercury deposits were found in the secretory granules.

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