Progenitor mobilization in chimeric mice. Animals chimeric for αMβ2 (αM^+/+ or αM^–/–) and enhanced green fluorescence protein (EGFP) expression were generated by bone marrow transplantation. Two months after transplantation mice were mobilized by a single injection of fucoidan. The numbers of nonfluorescent and green fluorescent colonies after 7 days of culture were determined using an inverted microscope equipped with a fluorescence source. (A) The ratios of EGFP-negative and EGFP-positive colonies were determined from mobilized colonies in the blood. Shown are mean ± SEM ratios. n = 6 from 2 independent experiments (Table 3). *P < .05 compared with the EGFP-αM^+/+ chimera. (B) A representative area containing colonies grown in methylcellulose media is shown using phase (top) or fluorescence microscopy (bottom) and a × 5 dry objective. EGFP-derived HPCs (arrowheads) can be distinguished from nonfluorescent colonies (arrows).