Nonadherent bone marrow cells engraft preferentially in metaphysis and epiphysis in the early regenerative phases after BMT. (A) Photomicrograph of a bone (Bo)/bone marrow (BM) section taken from the epiphysis of a mouse that underwent transplantation killed at 2 weeks after transplantation and stained with anti-GFP antibody (red). Original magnification, 100×. (B) Low level of GFP⁺ cells engrafted as clusters in the diaphysis, mainly in close proximity to the endosteal bone surface (asterisk). (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 GFP⁺ engraftment in the diaphysis versus the metaphysis/epiphysis at 2 weeks after transplantation. A total of 20 random 400× fields of bone sections from each of 4 mice were studied. The reported values are mean (+SD) percentages of GFP⁺ cells per field. The difference in engraftment is highly significant (P < .001). (E) Photomicrograph of a bone (Bo)/bone marrow (BM) section taken from the metaphysis of a transplanted mouse killed at 2 days after transplantation and stained with anti-GFP antibody (red). The cluster of early osteopoietic engraftment (arrows) is adjacent to donor (GFP⁺) hematopoietic cells (asterisk). Original magnification, 400×.