Patterns of bone engraftment with increasing time after transplantation of nonadherent bone marrow cells. Sections taken at 2 to 52 weeks after transplantation from different regions of bone (Bo) and bone marrow (BM) were stained with anti-GFP antibody (red). At 2 weeks, GFP⁺ osteoblasts (arrows) engrafted as clusters next to host (GFP⁻) osteoblasts in the epiphysis and in the metaphysis, while in the diaphysis the osteoblasts remained almost exclusively host derived. Beginning at 4 weeks, GFP⁺ osteocytes (dashed arrows) were consistently detected in both the metaphysis and epiphysis. At 8 weeks, in the metaphysis, in particular, Bo-embedded GFP⁺ cells could be identified under the growth plate (GP) as cell clusters. Again, the donor contribution was virtually undetectable in the diaphysis. At 24 weeks, a similar pattern of donor-derived osteopoiesis was evident. By 52 weeks, neither donor Bo nor BM contained GFP⁺ osteoblasts or osteocytes. The bottom row consists of photomicrographs of control (CTL) Bo/BM sections from a mouse that received a transplant of untransduced cells that were stained with anti-GFP antibody. Original magnification of all panels, 400×.