Histological appearance of the grafts in AOC 10 + sheep. (A) Line of fusion (arrows) in the interface between the distal portion of the cortical graft (right) and the host bone (left). (B) Corresponding site of a perforation of the cortical graft completely filled by well-organized bone formation. Arrows indicate the boundary of the former orifice. (C) Osteogenesis occurring in the inner portion of the graft. Bone trabeculae are covered by osteoid seams in close relationship with numerous active plump osteoblasts. (D) Adult adipocytes and classical hematopoietic cells are observed within the graft in the restored bone marrow. Masson-Goldner trichrome stain; 5- μm -thick undecalcified sections. Magnification 10× (A, under polarized light and C), (B) 4×, (D) 20×. Histological appearance of the graft in AOC 10 - sheep. (A) Gap between host bone and allograft containing fibrous connective tissue with no evidence of osteogenesis. (B) Interface between host bone and allograft displaying bone formation towards the inner portion of the medullary cavity (arrow). (C) The connective tissue that partially fills the central portion of the graft displaying a focal area of active osteogenesis intimately related with loose connective tissue, with the morphology of bone marrow supporting stroma (*). (D) Remainder of cancellous graft being actively resorbed by osteoclasts, without evidence of active bone formation. Masson-Goldner trichrome stain; 5- μm -thick undecalcified sections. Magnification (A-D) - 4×.