Dramatic reduction of cells in Flt3+ subsets of CLP and CMP fractions and DCps in the absence of CXCR4. E16.5 fetal liver cells (Ly5.2+/Ly5.1−) from CXCR4+/− and CXCR4−/− mice were transferred into lethally irradiated Ly5.2−/Ly5.1+ recipients. Flow cytometric analysis of the numbers of donor-derived Ly5.2+Lin−Sca-1+c-kit+ (LSK) Flt3lo primitive hematopoietic cells (A); progenitors of pDCs, including Ly5.2+Lin−IL-7R+Sca-1loc-kit+Flt3+ (Flt3+ CLP) and Ly5.2+Lin−Sca-1−c-kit+CD34+Flt3+ (Flt3+ CMP) cells; (B) and Ly5.2+CD11c+MHC II−CD4−CD8−CD19−NK1.1− DCp's (C) in the bone marrow of CXCR4+/− and CXCR4−/− chimeric mice 16 to 45 weeks after transfer (n = 3,5). Error bars represent SD of the mean.