Significant fetal hematopoiesis in juvenile mice with Pten deletion and leukemia. (A) Representative flow cytometry data from WT mouse blood at PND8 and 6 weeks (n = 4 each group). (B) Representative flow cytometry data from blood of WT mice and PtenΔ/Δ mice with leukemia at age 3 weeks (≥10 mice in each group). (C) Relationship between donor-derived (CD45.2⁺) progenies in PB and MZ/Fo B-cell ratios in spleens of recipients. (D) Representative flow cytometry data from blood and spleens of recipient mice transplanted from donor mice with various copy numbers of Pten and Nf1. GM [blood myeloid; CD45.2⁺CD11b⁺], (T+B) [blood lymphoid lineage; sum of CD45.2⁺B220⁺ + CD45.2⁺CD3e⁺], and blood myeloid/lymphoid ratios (GM/[T+B]) were calculated as ratios of myeloid cells/lymphocytes in total WBCs with CD45.2⁺ in recipient mice (CD45.1⁺). Fo, donor-derived follicular B cells are the predominant B cells in adults; MZ, donor-derived splenic marginal zone B cells representing fetal origin HSCs. The ratios of splenic MZ (fetal origin)/Fo (adult origin) B cells represented the fetal properties of donor HSCs. Data are median ± standard error. *P < .05, **P < .01, ***P < .001. See additional supportive data in supplemental Figures 8 and 10.