FIG. 3.

Normal cell cycle distribution during endogenous hematopoiesis but reduced numbers of primitive hematopoietic progenitors lacking Hoxb3/Hoxb4. (A) Hoxb3/b4^−/− BM cells and BM cells from control littermates were plated out in methylcellulose for measurement of CFU-C and BFU-E ability or injected into lethally irradiated recipients for CFU-S day 12 assay. The findings show a reduction in the absolute numbers of hematopoietic progenitors. The numbers of CFU/femur are shown for BFU-E and CFU-S, but the number of CFU-C is per 1/10 femur. Data from four different experiments are shown (mean ± the standard deviation [SD]; seven Hoxb3/b4^−/− and seven Hoxb3/b4^+/+ littermates). (B) The absolute numbers of LSK CD34 cells in the BM of both femurs was estimated by FACS analysis. A mild reduction in absolute numbers of LSK CD34⁻ cells was observed in mice deficient for Hoxb3 and Hoxb4. (C) The cell cycle distribution of LSK cells was analyzed by staining with Ki67 and 7AAD, enabling distinction and estimation of G₀, G₁, and S/G₂/M contents. No difference in cell cycle distribution was detected. The results from two experiments are shown (six mice/group). Shaded bars, Hoxb3/b4^−/−; solid bars, Hoxb3/b4^+/+.