Dissemination of leukemic cells into peripheral organs and tissues. (A) Hematoxylin and eosin staining of tissues from Bex/Vex control and leukemic CBFβ-SMMHC/FLT3-ITD mice. Data are representative of a minimum of 5 moribund CBFβ-SMMHC/FLT3-ITD animals. Original magnifications in the left and right columns for Bex/Vex and CBFβ-SMMHC/FLT3-ITD, ×150 and ×250, respectively, except for 3 panels that were at ×100 (left panels of control and CBFβ-SMMHC/FLT3-ITD spleen and left panel of control kidney) and 1 panel at ×500 (right panel of CBFβ-SMMHC/FLT3-ITD kidney). * Leukemic infiltrates in various tissues. (B) Representative sections of femur or spinal column stained with hematoxylin and eosin (original magnifications: bone: ×150, left panel; ×50 center panel; ×500 right panel; spinal column: ×50, left; ×50 center; ×500, right panel). SC indicates spinal cord; NB, nerve bundle. (C) Splenomegaly was observed in all CBFβ-SMMHC/FLT3-ITD mice (n = 17) (*). (Bar graph) Spleen weight (grams, means ± SD) for Bex/Vex controls (n = 6), CBFβ-SMMHC (n = 6), and CBFβ-SMMHC/FLT3-ITD mice (n = 7).