Endochondral Ossification

During endochondral ossification

• hyaline cartilage is replaced by bone

• hyaline cartilage turns into bone

• bone replaced by hyaline cartilage

• bone turns into hyaline cartilage

Endochondral ossification occurs

• in the irregular bones

• mainly in the bones below the skull

• only in the skull

• in flat bones

The chondrocytes near the center of the shaft enlarge and then die forming cavities

• Step 1: Collar bone formation

• Step 2: Cavitation

• Step 3. Diaphysis Elongation

• Step 4: Epiphyseal Ossification

Blood vessels penetrate the diaphysis

• Step 1: Collar bone formation

• Step 2: Cavitation

• Step 3. Diaphysis Elongation

• Step 4: Epiphyseal Ossification

Chondrocytes of the perichondrium turn into osteoblasts, the outside of the hyaline cartilage model is replaced by bone

• Stage 1: Bone Collar Formation

• Stage 2: Cavitation

• Stage 3: Diaphysis Elongation

• Stage 4: Epiphyseal Ossification

Blood vessels start to penetrate to the epiphyses to create secondary ossification centers

• Stage 1: Bone Collar Formation

• Stage 2: Cavitation

• Stage 3: Diaphysis Elongation

• Stage 4: Epiphyseal Ossification

The medullary cavity is completely formed, osseous tissue along the shaft becomes thicker, and an epiphyseal plate cartilage forms

• Stage 1: Bone Collar Formation

• Stage 2: Cavitation

• Stage 3: Diaphysis Elongation

• Stage 4: Epiphyseal Ossification

Capillaries and osteoblasts migrate to the epiphysis creating secondary ossification centers

• Stage 1: Bone Collar Formation

• Stage 2: Cavitation

• Stage 3: Diaphysis Elongation

• Stage 4: Epiphyseal Ossification

The epiphysis gets filled with spongy bone

• Stage 1: Bone Collar Formation

• Stage 2: Cavitation

• Stage 3: Diaphysis Elongation

• Stage 4: Epiphyseal Ossification

The epiphyseal cartilage starts to form; separation of the epiphysis from the diaphysis

• Stage 1: Bone Collar Formation

• Stage 2: Cavitation

• Stage 3: Diaphysis Elongation

• Stage 4: Epiphyseal Ossification