Analysis of hematologic parameters in PB and examination of the liver and spleen reveal no signs of leukemia in mice reconstituted with MLL-AF4–expressing CD34⁺ HSPCs. (A) Top panels: Absolute counts of WBCs, red blood cell, platelets, and hemoglobin in EV versus MLL-AF4 mice groups (n = 35). Bottom panels: Relative percentage of lymphocytes, monocytes, and neutrophils in the PB of EV and MLL-AF4–transplanted mice. The horizontal line indicates the median of each experimental group. (B) Weight and representative images of spleen and liver showing lack of splenomegaly and hepatomegaly in mice transplanted with MLL-AF4–expressing CD34⁺ HSPCs. (C) Hematoxylin and eosin staining (20×), displaying identical cellular composition and morphology of the spleens and livers from EV and MLL-AF4–transplanted mice (n = 35). Pictures were captured (20×/0.50 objective) with an Axiocam MRM digital camera (Zeiss) attached to an AxioImager AI microscope (Zeiss).