Most bones of the body

Bone formation preceded by cartilage model

Veiw Visual Step Chart to help memorize



1.  Mesenchyme cells form cartilage model

2.  Perichondrium surrounds cartilage model

3.  Osteoblasts differentiate on inner surface of perichondrium

4.  Collar of compact bone surrounds cartilage model on diaphysis of model

5.  Chondrocytes and lacunae in diaphysis enlarge (reducing amount of matrix)

6. Calcium deposits in remaining matrix (calcified cartilage)

7. Nutrients can’t diffuse

8. Chondrocytes die leaving hollow spaces

9. Blood vessels and osteoprogenitor cells enter matrix from periosteum

10. Osteoprogenitor cells differentiate into osteoblasts

11. Osteoblasts form bone matrix

12. This forms Primary Ossification Center in diaphysis

13. Secondary ossification center forms in epiphyses at time of birth or later