ENDOCHONDRAL OSSIFICSTION ( bone replaces cartilage)

Question 1

Step 1) Development of the cartilage model.

Answer 1

Development of cartilage model: mesenchymal cells develop into chondroblasts, which form the cartilage model ( which consists of hyaline cartilage). Periochondrium develops around the cartilage model.

Question 2

Step 2) Growth of the cartilage model.

Answer 2

Growth occurs by cell division of chondrocytes

Question 3

Step 3) Development of the primary ossification center.

Answer 3

In this region of the diaphysis, bone tissue has replaced most of the cartilage. Osteoblasts then begin to deposit bone extracellular matrix over the remnants of calcified cartilage, forming spongy bone trabeculae.

Question 4

Step 4) Development of the Medullary (marrow) Cavity.

Answer 4

Bone breakdown by osteoclasts forms the medullary cavity in the diaphysis. Eventually most of the wall of the diaphysis is replaced by compact bone.

Question 5

Step 5) Development of the Secondary Ossification Centers.

Answer 5

When branches of the epiphyseal artery enter the epiphyses . Spongy bone remains in the interior of the epiphyses , secondary ossification proceeds OUTWARD from the center of the epiphyses toward the other surface of the bone .

Question 6

Step 6) Formation of articular cartilage and the epiphyseal (growth) plate.

Answer 6

The hyaline cartilage that covers the epiphyses becomes the articular cartilage. Formation of articular cartilage and epiphyseal plate : both structures consist of hyaline cartilage.