Dot plot display of a typical Hoechst 33342 (X axis) and Pyronin Y (Y axis) staining of fresh bone marrow CD34⁺ cells (A). The three sort windows R1, R2, and R3 were constructed to collect G₀ , G₁ , and S/G₂ + M cells, respectively. After sorting, G₀ , G₁ , and S/G₂ + M cells, along with unsorted total CD34⁺ cells were stained with propidium iodide and analyzed for their cell-cycle distribution as described in Materials and Methods. B depicts the cell cycle distribution of total freshly isolated BM CD34⁺ cells with only 11% being in S/G₂ + M. C, D, and E illustrate the DNA content of sorted G₀ , G₁ , and S/G₂ + M cells, respectively. As can be seen, no cells were detected with greater than 2n DNA among G₀ and G₁ cells (C and D, respectively), whereas all sorted S/G₂ + M cells displayed a DNA content characteristic of their position in the cell cycle (E).