Ineffective erythropoiesis in HbSC and HbSS mice. (A) Splenomegaly was observed in HbSC and HbSS but not HbAA mice. (B) Representative flow cytometry density plots of bone marrow erythroid cells from HbAA, HbSC, and HbSS mice analyzed for forward scatter (FSC) and cell surface expression of Ter119 and CD71. Erythroid populations A (Ter119^highCD71^highFSC^high; basophilic erythroblasts), B (Ter119^highCD71^highFSC^low; late basophilic and polychromatic erythroblasts), and C (Ter119^highCD71^lowFSC^low; orthochromatic erythroblasts and reticulocytes) represent progressively more mature maturation stages. Dead cells, identified by DAPI staining, were excluded. (C) Summary of multiple flow cytometry studies of bone marrow performed as described for panel B. (D) Representative flow cytometry plots of bone marrow erythroid precursors stained for Ter119 and CD44. Populations I (proerythroblasts), II (basophilic erythroblasts), III (polychromatic erythroblasts), IV (orthochromatic erythroblasts and reticulocytes), and V (predominantly mature red cells) represent progressively more mature maturation stages. (E) Summary of multiple flow cytometry studies performed as described for panel D (HbAA, n = 3; HbSC, n = 3; HbSS, n = 3). Comparisons to HbAA mice are indicated in black; comparisons between HbSC and HbSS mice are indicated in blue. Data are presented as mean ± standard deviation; ∗P < .05; ∗∗∗P < .001. Ery, erythroid; ns, no significance; Pop, population.