Ultrastructural localization and in situ analysis of iron, bismuth, and gold inclusions

The purpose of this article is to review ultrastructural and electron probe X-ray analytical studies on metallic deposits in cells. The metals that will be dealt with are iron, bismuth, and gold, mainly because they have been extensively studied in recent years. The nature and chemical composition of endogenously (e.g., from breakdown of autologous blood) and exogenously (e.g., after a transfusion or injection of iron compounds) produced hemosiderin (i.e., iron deposits) has been the subject of time-hallowed controversies. Quite a few of these have now been resolved by ultrastructural studies and the atomic composition of such deposits has been determined by electron probe X-ray analysis. The interest in bismuth centers around the fact that this is one of the two metals (the other being lead) that produces quite large intranuclear inclusions. Here again much has been learned by ultrastructural and X-ray analytical studies. The interest in gold stems from the fact that soluble salts of this metal are used for the treatment of rheumatoid arthritis and current studies with the above-mentioned techniques indicates how gold produces its beneficial and toxic effects.