Endochondral ossification

Most bones of the fetus, such as limb bones, trunk bones, and skull base bones, are mainly formed by cartilage osteogenesis. This osteogenesis includes not only the similar process to the formation of intramembranous osteogenesis, but also the continuous growth and degradation of cartilage, as well as the unique process of cartilage tissue being continuously replaced by bone tissue. Osteogenesis is more complicated than in the membrane.