Abstract
Zinc (Zn II) and iron (Fe III) were demonstrated histochemically in cytoplasmic inclusions shown to be lysosomes in a number of cell types in Mytilus edulis. The cellular distribution of the metals differed between the sexes; males were shown to have more zinc (Zn II) in the kidney than females, the latter appearing to use oocytes as an additional means of excretion. Differences in cellular distribution of the metals was also demonstrated between the two populations studied probably reflecting availability of the metals in their respective environment.