The document discusses the stages of fracture healing, including: 1. Hematoma formation, proliferation of cells, and differentiation of cells to begin forming callus tissue. 2. The formation of an external callus from periosteum cells and an internal callus from bone marrow cells, which form irregular trabecular bone (callus) to bridge the fracture gap. 3. Remodeling of the callus over time through osteoblastic and osteoclastic activity to develop a stronger structure appropriate for mechanical stresses.