Phenotypic characterization of murine and human KL cells. (A) Murine KL cells from the AF (black bold solid line) and FL (gray normal solid line) were stained with antibodies specific for CD34, prominin-1, Thy1.2, H2Kb, Ly5.2, CD44, and Sca-1. Representative histograms for cells at E13.5 are shown. Am is not shown as it overlaps to FL for all the markers analyzed. Human AF (black bold solid line) and CB (gray normal solid line) KL cells were stained with specific mAbs for CD34, CD133, CD90, HLA-ABC, CD45, CD44, and HLA-DR. For both murine and human cells, the control isotype is indicated in light gray. (B) Analyses of murine KL cell-cycling status. Cells from wild-type C57BL/6 embryos were harvested 2 or 24 hours after the first administration of BrdU at E12.5. BrdU incorporation by Lin⁻ cells was detected by fixation, permeabilization, and staining with a fluorescein isothiocyanate–conjugated anti-BrdU Ab. The results of 1 of 2 experiments are shown.