Bone growth occurs in several stages:
Intramembranous Ossification: Bone develops directly from sheets of mesenchymal connective tissue (e.g., flat bones like the skull).
Endochondral Ossification: Bone develops by replacing hyaline cartilage (most bones, including long bones).
Growth in Length: Occurs at the epiphyseal plates, where new cartilage is produced and then replaced by bone.
Growth in Width: Occurs through appositional growth, where new bone tissue is added to the surface of the bone.