Bone- development Flashcards
What are the two types of ossification?
Endochondral (most common type incl. long bone growth)
Intramembranous (flat bones of skull, mandible, maxilla, but also long bones)
Most bones are formed by a combination of both types!
What happens in endochondral ossification?
-Endochondral - means bone forms within cartillage
Bone forms as cartilage ‘model’ first
Blood vessels invade cartilage
Cartilage replaced with bone
Cartilage remains in epiphyseal growth plate
Growth plate eventually ossifies
What happens in intramembranous ossification?
No cartilage ‘model’!
Mesenchymal cells develop into osteoprogenitor cells that mature into osteoblasts that start depositing bone
Residual mesenchymal cells develop blood vessels & bone marrow
This bone formation also occurs in adult bone
What are two types of bone growth? (for bone to be larger)
Appositional growth
- The diameter of long bone shaft increases
-osteoblasts on outside for new bone and diameter increase
-bone on inside resorbed by osteoclasts
Interstitial growth
-long bone grows in length due to epiphysial growth plate
-Endochondral ossification
