MDS and AML is observed in animals transplanted with RUNX1(41-214)–expressing cells. (A) Peripheral blood parameters of moribund animals transplanted with RUNX1(41-214)–expressing cells (●) at the time of death. Values of healthy MigR1 animals (○), killed at the same time, are shown as control. (B) Histopathologic analysis of BM of MigR1 and RUNX1(41-214) animals. HE staining of BM is shown at original magnification of ×200 and ×1000. Reticulin staining of BM is shown at original magnification of ×200. Arrows point to reticulin fibers stained in black. (C) Histopathologic analysis of SP of MigR1 and RUNX1(41-214) animals. HE staining of SP is shown at original magnification of ×100. (D) SP weight of MigR1 (○) and RUNX1(41-214) animals (●) at the time of death. (E) Representative flow cytometric analysis of total BM of animals that received a transplant with MigR1 and RUNX1(41-214). (F) Cytologic analysis (Wright-Giemsa staining) of RUNX1(41-214) animals: (Fi) hypersegmented neutrophil in peripheral blood; arrow points to Howell-Jolly body in red blood cell; (Fii) Perger-Huët anomaly in peripheral blood, also note polychromasia and anisocytosis in red blood cells; (Fiii) binucleated neutrophilic metamyelocyte; (Fiv) trinucleated neutrophilic metamyelocyte; (Fv) micromegakaryocyte; (Fvi) binucleated prorubricyte (original magnification, ×1000). WBC indicates white blood cells; MCV, mean corpuscular volume; HE, hematoxylin-eosin; and SP, spleen. All images were acquired with BX51 microscope with objective lenses 10× PlanFLN/0.3, 20× PlanFLN/1.42, 100× PlanFLN/1.3, equipped with DP71 digital camera (Olympus).