Altered cycling and apoptosis of lymphoid precursors after Hhex deletion. (A) Flow cytometric analysis showing proportions of HSC, LMPP, and CLP populations in lineage-depleted BM of the indicated Hhex genotypes. (B) Combined data showing numbers of HSCs, LMPPs, and CLPs per million BM cells, analyzed, as in (A). *P < .05 by Student t test. (C-D) The percentage of annexin-V⁺ apoptotic cells in hematopoietic progenitors (C) and developing B-cells (D) in the BM, assessed by flow cytometric analysis. Hardy B-cell fractions were gated as in (supplemental Figure 2A). (E) Representative histograms showing DNA content of CLPs of the indicated Hhex genotypes, as measured by DAPI staining. (F) Percentages of cycling (>2N) cells in hematopoietic progenitors in the BM, measured by 4,6 diamidino-2-phenylindole staining and flow cytometry, as in (E). (G) Representative histograms showing 5-bromo-2′-deoxyuridine incorporation in the indicated B-cell populations 20 hours postinjection, gated, as in (supplemental Figure 2B). (H) Percentages of 5-bromo-2′-deoxyuridine–positive cells in the indicated B-cell populations, measured by flow cytometry as in (G). *P < .05, Student t test.