FLT3^wt/ITD, FLT3^−/ITD, and FLT3^ITD/ITD mice develop progressive MPN. (A) Spleen (i-iv), liver (v-viii), and BM (ix-xii) from representative mice. (xii) Arrows indicate cells with aberrant mitoses. Scale bars are as follows: i-viii, 100 μm; ix-xii, 10 μm. Images for hematoxylin and eosin stain were acquired at room temperature using a Zeiss Axioskop upright microscope system (Carl Zeiss) with Achroplan 5×/0.16 NA, 10×/0.3 NA, and 40×/0.6 NA objectives and were photographed with an AxioCam camera (Carl Zeiss) and Axiovision Version 4.0 software (Carl Zeiss). Immunophenotype of BM from FLT3/ITD genotype mice demonstrates enhanced expansion of granulocytes/monocytes (B) and block of B-lymphoid development (C). Flow cytometric analysis of BM cells from representative 2-month-old FLT3^wt/ITD, FLT3^−/ITD mice, and a representative 3-week-old FLT3^ITD/ITD mouse. Numbers indicate percentage of cells in whole BM.