Abstract Eosinophils from Japanese quail exhibit characteristic vacuoles when blood smears are stained with May-Grunwald-Wright stain and when fresh blood preparations are stained with neutral red. These vacuoles are the distinguishing trait of this leucocytic cell-type in Japanese quail. Thus, eosinophils in Japanese quail can be differentiated from heterophils and eosinophils in the chicken and other avian species.