Human and murine erythroblasts undergo comparable progressive stages of maturation characterized by changes in cell size, nuclear condensation, and loss of cytoplasmic basophilia. These features are used to classify the cells as proerythroblasts (ProE), basophilic erythroblasts (BasoE), polychromatophilic erythroblasts (PolyE), and orthochromatic erythroblasts (OrthoE). All erythroblast images were kindly provided by Dr Xiuli An, New York Blood Center, with mouse erythroblast images adapted from Liu et al.8 All images were color corrected and cropped by J.P.
