Fig 4. In the control group, intense bone deposition occurred at the defect site.

A significant bone callus formation (arrows) was observed in the membrane groups, with interconnected trabeculae and robust regeneration of hematopoietic marrow. The membrane space still contained remnants of the exogenous material beneath the periosteum (black circle) (Hematoxylin-eosin, original magnification X 100). Osteoclasts (white arrows) were also observed in the bone callus (E) (TRAP, original magnification 400X).