Phenotypic analysis of early hematopoietic progenitors after osteoblast depletion. Cell suspensions from bone marrow, spleen, and liver were prepared from transgenic mice treated for 25 days with PBS (top contour plots) or GCV (bottom contour plots). Cells were stained with a cocktail of antibodies labeled with phycoerythrin and reactive against mature hematopoietic lineage components (lymphocytes, macrophages, granulocytes, erythrocytes). The cells were subsequentially stained with 2 antibodies reactive with early hematopoietic progenitors (Sca-1 coupled to fluorescein isothiocyanate [FITC] and cKit coupled to allophycocyanin). The figure shows representative contour profiles of the reactivity for progenitor markers in populations negative for lineage markers. The framed regions are the areas corresponding to cells with HSC phenotype, and the number shows the percent of cells contained within the Lin^- population.