Cytology of the bone marrow in the Mongolian gerbil

Heterophils were the most numerous cells (39%), followed by the normoblasts (27%) and lymphocytes (8%). Significant differences between males and females were observed in the total number of heterophils (42 and 35% respectively, P less than 0.002), heterophil myelocytes (12 and 10%, P less than 0.01) and the myeloid:erythroid ratio (1.9:1 and 1.4:1, P less than 0.03). Heterophils presented both annular and polymorphous nuclei, which appeared to develop along separate lines. The ring series began with a small nuclear 'vacuole' which increased in size with maturation of the cell. Ring-forms comprised 1/3 of the total heterophil population in the marrow. Eosinophils and basophils also demonstrated annular nucleated forms. Mature heterophils tended to have a scarcity of stainable specific granulation. Eosinophil granules were larger than those of the heterophil, slightly refractile and did not react avidly with eosin. Basophil granules, conversely, reacted strongly with the methylene-blue component of Wright-Giemsa stain and were metachromatic. Normoblasts retained their cytoplasmic basophilia to a greater degree than comparable cells in man.