Definition of the myeloid subsets in bone marrow of wild-type FVB/N mice. (Ai) Cells expressing Sca1, CD45/B220, CD19, CD8, and CD4 were depleted with antibodies. Expression of CD34 and c-kit defined 2 populations (Aii). Each of these 2 populations (CD34⁺/c-kit⁺ and CD34⁻/c-kit⁻) was sorted according to expression of Gr1 and FcγRIII/II and divided into 4 subpopulations (1-4; Aiii) for cells isolated from the CD34⁺/c-kit⁺ fraction and 5 subpopulations (5-9) for cells isolated from the CD34⁻/c-kit⁻ fraction (Aiv). (B) Sorted cells from CD34⁺/ckit⁺ exhibit the morphology of myeloblasts to promyelocytes (subpopulation 1-4), whereas sorted cells from CD34⁻/c-kit⁻ exhibit the morphology of increasingly mature myeloid cells from metamyelocytes to mature “band cells.” Sorted cells were subjected to Wright-Giemsa staining, and pictures were acquired at an original magnification ×100 with oil. Numbers in each panel represent the 9 fractions shown in Aiii and iv. (C) Expression of cathepsin G (a primary granule gene), lactoferrin (a secondary granule gene), and MMP9 (a tertiary granule gene) in CD34⁺/ckit⁺ and CD34⁻/c-kit⁻ sorted cells demonstrate a pattern of granule gene expression correlating with their morphology. Gene expression was assessed by quantitative real-time PCR and normalized to GAPDH levels. Numbers on the x-axis represent the 9 fractions shown in panels Aiii and iv.