Cadmium in the gastropod Littorina littorea

Abstract

Tissues of Littorina littorea (Mollusca: Gastropoda) were processed for electron microscopy with an aqueous fixative which included hydrogen sulphide to precipitate intracellular cadmium. The procedure retained cadmium in the cytosol, where it was below the detection limit for x-ray microanalysis, but it did not increase the retention of the metal within lysosomes and other sites of accumulation where it was detectable. Aqueous fixation caused extraction of labile elements, particularly magnesium and potassium, and this effect was increased by the use of hydrogen sulphide. Cadmium and hydrogen sulphide had disruptive effects on the fine structure of cells. It is concluded that cytological fixatives should not include hydrogen sulphide, and that cryo-fixation is required for x-ray microanalysis of intracellular elements.