Bone grows through the processes of intramembranous and endochondral ossification. Intramembranous ossification develops bone directly from connective tissue, while endochondral ossification replaces cartilaginous skeletal parts with bone. During endochondral ossification, hyaline cartilage is present near the epiphyses of long bones and breaks down as cartilage cell columns are replaced by osteoblasts depositing new bone tissue. Bone age can be determined by examining an x-ray of the epiphyseal plates and timing of their fusion with the diaphyses, which occurs at different ages for each bone.

2. Osteocytes

3. Osteoclasts

4. osteoid

6. Long bone growing in length Long bone growing in width Osteoclasts remove bone tissue Osceocytes produce new bone tissue

7. Bone healing After fracture bone must be lined to original position Callus is formed to hold bone in place Callus made of collagen Callus calcifies And absorbed and replaced by bone

8. Ossification Two types: intramembranous endochordral Intramembranous ossificationis the development of bone from connective tissue Mesenchymal cells osteoblasts osteocyte Osteoclasts grow along, functioning in the removal and absorption of osseous tissue Chondral ossification cartilaginous skeletal parts replaced by bone

9. Endochondral ossification Two types: Endochondral Perichondral Endochondral ossification near epiphyses (end of long bone) Hyaline cartilage present at articular surfaces Cartilage cell columns Break down of cartilage replaced by osteoblasts Perichondral perichondrium at diaphysis

10. Bone age Can be determined by studying epiphysis and diaphysis on x ray Disappearance of epiphyseal line fusion Fusion occurs at different time for each bone Thus, able to determine age