A brief presentation on endochondral ossifcation. dealing with cellular changes in bone and physiological process involved in long bone developmen

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2. Endochondral ossification
• Definition- the process of formation of long
compact bone from hyalin chondrocytes
cartilage model is known as endochondral
ossification
This process begins between the sixth and seventh
weeks of embryonic development and
continues until about age twenty-five
Cartilage model Mature long bone

3. 1. Formation of cartilage model
Mesenchymal cells (stem cell) migrate and differentiate to form chondroblast which matures
into chondrocyte to form a hyaline cartilage model
MESENCHYMAL STEM CELL CHONDROBLAST CHONDROCYTE CARTILAGE MODEL

4. Mesenchymal stem cell
osteoblast
Osteoid
Bone collar formation
Mesenchymal cells of Perichondrium
differentiates into Osteoblast which secretes
osteoid (mineral component) which forms the
bone collar at the periphery of the diaphysis
of newly formed cartilage model
The chondrocyte dies and secretes VGEF that
stimulate angiogenesis and periosteal bud
formation
2. Formation of bone collar

5. Periosteal buds (later becomes Nutrient Artery) invade the
center of the diaphysis. Through Nutrient Foramen.
Vascularization occurs via the periosteal bud, which
brings forth osteoprogenitor cells (Osteoblast and
osteoclast) forming the primary ossification center, which
forms within the cavities that are created when the
hypertrophic chondrocytes dies.
Osteoblast forms the bone along the length and osteoclast
destroys the dead chondrocytes forming the medullary
cavity in the center
3. Formation of primary ossification center
Osteoclast
forming
medullary
cavity
Osteoblast
forming
new bone

6. 4. Formation of secondary ossification center and periosteum
Blood vessels and osteoprogenitor cells enters the
Epiphyses and converts Hyaline cartilage to Songy
bone and the cavities is filled with blood forming RED
MARROW
ZONE OF PROFILERATION IN EPIPHESYEAL PLATE
helps bone to grow longitudinally (interstitial
growth)
Where as the formation of compact bone within
the periosteum by the help of Osteoblast helps in
appositional growth (growth in diameter and
width)
©copyright anurag joseph