l l l RED CELLS, IRON, & ERYTHROPOIESIS Comment on An et al, page 3466 Of mice and men…

In this issue of Blood, An et al provide human and murine transcriptome data revealing significant stage- and species-specific differences in gene expression during erythroblast maturation.1 The process of erythroblast maturation ischaracterized by a progressive decrease in cell size, nuclear condensation and ultimate extrusion (in mammals), and the loss of cytoplasmic basophilia due, in part, to the accumulation of hemoglobin. As shown in the figure, these striking morphological features have been used by hematologists in the clinic to classify erythroblasts in disease states and by investigators in the laboratory to study erythroid maturation both during development and across species. The overarching similarities of this morphological process both in humans and i