Vacuoles are areas of the cytoplasm which do not stain with Wright's stain and appear as holes in the cytoplasm. Their composition may vary; some will contain remnants of bacterial digestion, autodigestion in an aging cell, while still others may contain fat. It is not possible to differentiate the various types of vacuoles on Wright's stained smears under light microscopy. They may be seen occasionally in an aging granulocyte, but are seen more frequently and are significant in cases of bacterial infection and septicemia.