Hmga2 expression augments BM cells and HSCs with enhancing extramedullary hematopoiesis in JAK2^V617F-induced MPN. (A) The total nuclear cell numbers from the ground right femur (×10⁷). N = 3 for each. (B) The ratio of each fraction in BM by fluorescence-activated cell sorter (FACS; percentage in all gated cells) is shown. N = 5 for WT, 5 H, 4 J, and 3 HJ mice. (C) Ratios of differentiated cells in BM (percentage in all gated cells). N = 3 for each genotype. (D) Sternal BM histology. Hematoxylin and eosin (top and middle) and silver (bottom) stains. Scale bars indicate 500 μm (top; original magnification ×40) and 50 µm (middle and bottom; original magnification ×1000). (E) Mean megakaryocyte counts in high-powered field (Meg/HPF; ×400). Mean of 5 fields are shown in each genotype. (F) Spleen weight (N = 4, each genotype). (G) Representative picture of the spleens from the littermates. (H) Histology of spleens (hematoxylin and eosin stain). Scale bars indicate 500 µm (original magnification ×40). (A-C, E-F) Bars show the means ± SEM. *P < .05; **P < .01; ***P < .001 (Tukey-HSD test). B220, B220⁺ B cell; CMP, common myeloid progenitor cell; EBL, CD71⁺Ter119⁺ erythroblast; GMP, granulocyte-macrophage progenitor cell; H, ΔHmga2; HJ, ∆Hmga2/JAK2^V617F; J, JAK2^V617F; LateEBL/Ret, CD71⁺Ter119^dim late erythroblast/reticulocyte; MEP, megakaryocyte-erythroid progenitor cell; Myeloid, Gr-1⁺ myeloid cell; N.S., not significant; T, TCR⁺ T cell.