Osteoblasts and Osteocytes

Abstract

Bone is a specialised form of the connective tissue characterised by impregnation of the extracellular matrix with salts of calcium and phosphate. Mineralisation is connected mainly with the apposition of hydroxyapatite crystals onto both components of the ground substance and collagen fibrils and leads to a special strength and stability of the tissue making it particularly qualified for providing support and protection for the body and its organs. Another important function of bone is to establish a reservoir for calcium and phosphate ions. Bone is highly vascularised and holds a crucial role in the regulation of blood calcium levels. Although it appears rigid and inflexible, it is metabolically very active and sensitive to functional alterations and changes of load, which result in a reorganisation of the tissue and reconstruction of the bone skeleton. Bone undergoes continuous remodelling associated with resorption, new production of mineralised matrix, and neovascularisation not only during development but also in the adult bone skeleton according to functional conditions.