Flow cytometric analysis of CD34⁺, CD38⁻, CD45⁻ adult bone marrow cells. Suspensions of low density mononuclear cells from human adult bone marrow were stained with fluorescently labeled monoclonal antibodies. CD34⁺ cells were collected into a list mode data file and analyzed using the Paint-a-Gate Plus program (BDIS). The axis of each panel is labeled according to the light scatter parameters examined, or the antigen recognized by the monoclonal antibody used, and the corresponding fluorescence conjugate (ie, CD38 Cychrome). The putative stromal cells (CD34⁺, CD38⁻, CD45⁻) were present at frequency of 0.5% and were shown as a large block dots, while CD34⁺ hematopoietic progenitors are shown as smaller gray dots.