Final answer:
Bone formation occurs during growth, healing after injury, adapting to stress, and embryonic development. The repair of a broken bone undergoes four stages, which include the formation of a hematoma, fibrocartilaginous callus, bony callus, and remodeling of bone.
Step-by-step explanation:
Bone Repair and Formation
Bone formation can occur in several scenarios, particularly during growth, after injury, or when adapting to stress. In the case of bone repair following a fracture, there are four stages to this process:
The formation of a hematoma at the break site.
The formation of a fibrocartilaginous callus.
The formation of a bony callus.
The remodeling of bone, where the healed bone is restored to its original shape.
Bone to adapts to stress through bone remodeling, which involves bone deposition by osteoblasts and resorption by osteoclasts. When bones do not receive normal stress, such as when immobilized in a cast, they may lose mass. This process can be influenced by diet, age, pre-existing bone conditions, and hormonal changes.
In addition to injury repair, bone formation occurs during ossification in embryonic development, as cartilaginous structures are replaced by bone, and during growth via activity at the epiphyseal plates. New bone is formed by osteoblasts, which originate from osteogenic cells and eventually become trapped in the bone matrix as osteocytes, the cells of mature bone.