Structure and morphology of bone tissue, structural and functional
organization of bone
Bones are an extremely dense specialized form of connective tissue. Connective
tissue cells, including fibroblasts, cartilage and bone cells, specialize in the
secretion of fibrillar proteins (primarily collagens), which are used for the
construction of intercellular matter. The intercellular matrix is a complex substance
that is located in the interstitial interstitial space (between cells). In connective,
cartilage and bone tissue, the intercellular matrix occupies a significant volume and
performs the main functions.
Bone formation
Cells of mesenchymal origin — fibroblasts, osteoblasts-synthesize and secrete
collagen fibrils, which are located in the matrix, which also contains proteoglycans
and glycosaminoglycans (White A. et al., 1981a). Mineral components come from
the surrounding liquid phase, the formation of a crystal lattice is induced by
nucleation (activates the formation of crystals of three-stranded collagen). Bone
formation begins between the collagen fibrils, where apatite structures are built
(biomineralization occurs). The crystals become nucleation centers for the
deposition of hydroxyapatite and collagen induces the deposition of calcium.
Proteoglycans increase the extensibility of the collagen network, increasing
swelling. Bone formation occurs near osteoblasts. In the calcification zone,
degradation of protein — polysaccharide complexes is noted. Growing crystals
displace proteoglycans and water (the formed bone is dehydrated). 20% of the
bone mass and 40% of the volume is made up of collagen. In the structure of the
bone substance, there are Haversov channels lined with cells that conduct blood
, vessels. Bone is a dynamic calcium depot, while the constancy of the bone
structure ensures the activity of osteoblasts and osteoclasts. The large contact
surface of the crystals of mineral components of bone tissue with the intercellular
fluid ensures the rapid entry of various cations into the bone. The crystals are
hydroxyapatites or carbonatapatites, which are the most important mineral
component of bone tissue and whose composition reflects the formulas Ca10
(PO4)6 (OH) 2 and Ca10(PO4)6CO3. The bones contain carbonates of other
alkaline earth chemical elements. Apatite is a large complex cation Ca
[Ca3(PO4)2]32+, which is surrounded by counterions OH -, CO32 -, HRO42 -, F -.
The crystals have the form of plates or rods with a thickness of about 815 °A, a
width of 20-40, a length of 200-400. In the crystal lattice of hydroxyapatite, calcium
can be replaced by other divalent cations. Anions are adsorbed on the surface,
which is formed by small crystals, or dissolved in the hydrate shell of the crystal
lattice. A protein (49 amino acid residues) containing three gamma-carboxyglutamic
acid residues is strongly bound to the hydroxyapatite crystals. This protein is
involved in the regulation of calcium binding in bones and teeth.
organization of bone
Bones are an extremely dense specialized form of connective tissue. Connective
tissue cells, including fibroblasts, cartilage and bone cells, specialize in the
secretion of fibrillar proteins (primarily collagens), which are used for the
construction of intercellular matter. The intercellular matrix is a complex substance
that is located in the interstitial interstitial space (between cells). In connective,
cartilage and bone tissue, the intercellular matrix occupies a significant volume and
performs the main functions.
Bone formation
Cells of mesenchymal origin — fibroblasts, osteoblasts-synthesize and secrete
collagen fibrils, which are located in the matrix, which also contains proteoglycans
and glycosaminoglycans (White A. et al., 1981a). Mineral components come from
the surrounding liquid phase, the formation of a crystal lattice is induced by
nucleation (activates the formation of crystals of three-stranded collagen). Bone
formation begins between the collagen fibrils, where apatite structures are built
(biomineralization occurs). The crystals become nucleation centers for the
deposition of hydroxyapatite and collagen induces the deposition of calcium.
Proteoglycans increase the extensibility of the collagen network, increasing
swelling. Bone formation occurs near osteoblasts. In the calcification zone,
degradation of protein — polysaccharide complexes is noted. Growing crystals
displace proteoglycans and water (the formed bone is dehydrated). 20% of the
bone mass and 40% of the volume is made up of collagen. In the structure of the
bone substance, there are Haversov channels lined with cells that conduct blood
, vessels. Bone is a dynamic calcium depot, while the constancy of the bone
structure ensures the activity of osteoblasts and osteoclasts. The large contact
surface of the crystals of mineral components of bone tissue with the intercellular
fluid ensures the rapid entry of various cations into the bone. The crystals are
hydroxyapatites or carbonatapatites, which are the most important mineral
component of bone tissue and whose composition reflects the formulas Ca10
(PO4)6 (OH) 2 and Ca10(PO4)6CO3. The bones contain carbonates of other
alkaline earth chemical elements. Apatite is a large complex cation Ca
[Ca3(PO4)2]32+, which is surrounded by counterions OH -, CO32 -, HRO42 -, F -.
The crystals have the form of plates or rods with a thickness of about 815 °A, a
width of 20-40, a length of 200-400. In the crystal lattice of hydroxyapatite, calcium
can be replaced by other divalent cations. Anions are adsorbed on the surface,
which is formed by small crystals, or dissolved in the hydrate shell of the crystal
lattice. A protein (49 amino acid residues) containing three gamma-carboxyglutamic
acid residues is strongly bound to the hydroxyapatite crystals. This protein is
involved in the regulation of calcium binding in bones and teeth.
