The extracellular matrix is characterized by abundant collagen fiber bundles. High levels of hyaluronic acid are present. Cells of mesenchyme have large, euchromatic nuclei with prominent nucleoli. Mitotic figures within lacunae can be seen in bone but not in cartilage. Cartilage can grow appositionally but bone cannot.
Bone contains more and larger proteoglycans than does cartilage.
Type II collagen is present in cartilage, but not in bone. It is poorly vascularized. Macrophages are characteristically present. Type I collagen. The cellular content may be variable.