The osteopoietic capacity of nonadherent bone marrow cells is preserved in secondary recipients. Immunohistochemical identification of donor-derived bone cells (arrows) in primary (A) and secondary (B) recipients. (C) Section of bone from a mouse that received a transplant of untransduced nonadherent marrow cells and stained with anti-GFP antibody (negative control). (D) Comparison of the percentages of donor-derived osteopoiesis in primary (n = 3 mice) versus secondary (n = 10 mice) recipients. The reported values are mean (± SD) percentages of GFP⁺ cells. Bone engraftment was quantified as described in Figure 3; P > .05.