Abstract
Basophilic stippling of the circulating erythrocytes is characteristic of the Mongolian gerbil. Its enzymatic digestion along with the concomitant removal of diffuse erythrocytic polychromasia by the action of ribonuclease demonstrates that it represents microscopically visible aggregates of cytoplasmic ribonucleoprotein, presumably of ribosomal origin. Up to 40% of the total circulating erythrocytes may be stippled in foetal and newborn animals. There is then a progressive decline in incidence until adult levels are attained at least by 20 weeks of age. The bone marrow of the adult gerbil contains a higher proportion of stippled red cells than the circulating blood. The stippling can be either coarse or fine and observable in both polychromatophilic and orthochromic cells. It is suggested that erythrocytes with basophilic stippling are relatively immature red cells still demonstrating remnants of cytoplasmic ribonucleoprotein.