Explain the endochondral ossification
The second type of osteogenesis is endochondral ossification. This process is different from intramembranous ossification in that it occurs with a cartilage base. Endochondral ossification is responsible for a good deal of formation of the long bones , vertebrae and portion of the mandible. It occurs in the following steps: Embryonic mesenchymal stem cells differentiate into a primitive hyaline cartilage. Blood vessels and bone- forming units, which resorb the cartilage and replace it with osteoid, invade this matrix.