Metal-Containing Blood Cells of Oysters: Ultrastructure, Histochemistry and X-Ray Microanalysis

The ultrastructure, histochemistry and X-ray microanalysis of the metal-containing blood cells in three species of oyster,Ostrea edulis, Ostrea angasiandCrassostrea gigasare described. Granular cells containing both copper (up to 400 mM) and zinc (up to 1 M) are present in all three species. In addition,Ostrea edulishas two other granular amoebocyte types which specifically accumulate either copper (400 mM) or zinc (12 M). In all types of amoebocyte, the metals are stored in membrane-limited vesicles. The ultrastructure and histochemical staining characteristics of the vesicular contents vary according to metal composition. Zinc-containing granules appear basophilic after sulphide treatment and display homogeneous electron density; copper/zinc-containing granules are less dense and show varying degrees of crystallinity; copper-containing granules appear crystalline (however, any acidophilic or basophilic reaction is masked by the dark brown precipitate of copper sulphide).