Transmission Electron Microscope image of the gastrodermis (syncytial absorptive gut lining) of an adult female Schistosoma japonicum. The parasite was fixed in 3% glutaraldehyde in cacodylate buffer supplemented with 5% tannic acid, followed by fixation in osmium tetroxide and embedded in Spurr's resin. Hemozoin formation in the schistosome gut occurs in structure believed to be epicellular vacuolar compartments (or luminal pockets of the gastrodermis-see Delcroix et al. ) formed by extensive growth of surface lamellae of the syncytial lining. A. Micrograph of apical region of the gastrodermal syncytium showing abundant epicellular vacuolar compartments (arrows). The pale bodies (H) in the lumens of the vacuoles are regions of hemoglobin. The dark bodies (Hz) are hemozoin crystals. B. Enlargement of boxed region of A. Hemozoin forms at the surface of lipid particles. Abbreviations: H-fragment of erythrocyte; Hz-hemozoin; L-lamella of gastrodermis.