Histological appearance of the graft in AOC 6 - sheep. (A) Orifice corresponding to the perforation of the cortical graft only partially filled with new bone formation. (B) Intact allogeneic bone graft represents most of the filling of the inner portion of the graft. (C) Portions of the filling of the graft are represented mostly by connective tissue with no evidence of active osteogenesis. (D) Osteogenesis, when identified in the inner portion of the implant, is represented by partially mineralized bone trabeculae (osteoid seams stained in red). Masson-Goldner trichrome stain; 5-mm-thick undecalcified sections. Magnification (A-D) - 4×. Histological appearance of the graft in AOC 6 + sheep. (A) The site of the perforation in the cortical graft is filled by well-connected thick bone trabeculae displaying high osteoblastic activity through practically the entire length of the trabecular surfaces. (B) Cortical graft undergoing remodeling (cutting cone). (C) Focal area of active osteogenesis localized in the connective tissue that fills the central portion of the graft. (D) Bone formation in close association with loose connective tissue featuring characteristics of bone marrow supporting stroma. Masson-Goldner trichrome stain; 5-μm-thick undecalcified sections. Magnification 10× (A and B), 4× (C and D).