Bone
Mineralisation
Image obtained from Wheater's Functional Histology, Young and Heath Editors, Churchill Livingstone Publishers, 2002
- Active osteoblasts secrete osteoid collagen (red) and matrix vesicles (yellow)
- Matrix vesicles contain alkaline phosphatase and pyrophosphatase - produce phosphate ions
- Mature compact bone contains 70% inorganic salts, 30% organic matrix
- Collagen is 90% of the organic matrix the rest is proteoglycans and non-collagenous proteins
- Bone collagen is 50% of the total body collagen - type 1 only
- Less proteoglycans than in cartilage and are mainly chondroitin sulphate and hyaluronic acid
- Non-collagenous proteins - osteocalcin, osteonectin and sialoproteins