seven to nine days after fracture, the cells of the periosteum replicate and transform. the periosteal cells proximal to (on the near side of) the fracture gap develop into chondroblasts, which form hyaline cartilage. the periosteal cells distal to (at the far end of) the fracture gap develop into osteoblasts, which form woven bone through bone resorption of calcified cartilage and recruitment of bone cells and osteoclasts. the fibroblasts within the granulation tissue develop into chondroblasts which also form hyaline cartilage. these two new tissues grow in size until they unite with each other. these processes culminate in a new mass of heterogeneous tissue known as a fracture callus callus formation peaks at day 14 of fracture. eventually, the fracture gap is bridged