In vivo Ho uptake by BM HSCs and multipotent progenitor cells according to their CD34 and FLT3 expression profiles. 129SvJ mice were perfused with Ho dye intravenously 10 and 5 minutes before tissue sampling, and BM was processed exactly as described in Figure 1. BM cells were stained for lineage, CD41, Sca-1, KIT, CD34, and FLT3 surface antigens. (A) Dot plot of CD34 versus FLT3 expression on viable 7-amino-actinomycin D⁻ LSK CD41⁻Sca-1⁺KIT⁺ cells. (B-D) Representative dot plots of Ho blue fluorescence versus Ho red fluorescence of gated viable LSK CD41⁻CD34⁻FLT3⁻ long-term reconstituting HSCs, LSK CD41⁻CD34⁺FLT3⁻ short-term reconstituting myeloid progenitors, and LSK CD41⁻FLT3⁺ short-term reconstituting lymphoid progenitors, respectively. (E) Distribution of Hoechst bright, medium, and negative cells among LSK CD41⁻CD34⁻FLT3⁻ (CD34- FLT3-), LSK CD41⁻CD34⁺FLT3⁻ (CD34+ FLT3-), and LSK CD41⁻FLT3⁺ (FLT3+) populations. Data are average ± SD from 3 mice.