Fewer IL-7R–positive cells in the progeny of My-bi HSCs. Shown are immunofluorescence plots of spleen cells stained for CD127 (IL-7R) and the donor-type marker CD45.1 from control mice (A) and chimeric mice that had received My-bi (B), balanced (C), or Ly-bi (D) HSCs 7 months earlier. Percentages of IL-7R–positive cells among the donor-type cells are indicated above the gates. Absolute numbers of donor-type cells were 34.7, 57.8, and 46.1 for mice shown in panels B, C, and D, respectively. Mean fluorescence levels for donor- and host-type cells of IL-7R–positive cells are shown in Table 2.