Comparative analysis of the interactions of CD34+ cells with BM microvessels in NOD/SCID mice. Fluorescently labeled CD34+ cells from steady-state human BM, mPB, or CB were injected into NOD/SCID mice, and the numbers of cells interacting (rolling or arrested) with the BM microvasculature were determined by analysis of video recordings from fluorescence intravital microscopy experiments. n = 7–10 mice and human donors. *P < 0.02 compared with BM and mPB. **P = 0.03.