The Bone Matrix

Bone is a supportive connective tissue with the major bulk made up of matrix components, and only 2 to 3 percent of mass contributed by cells.

About two-thirds of the matrix comprises inorganic salts, and one-third is made of the organic component called osteoid.

The osteoid is mainly composed of the fibrous protein collagen, along with glycoproteins such as proteoglycans.

While collagen provides structure and elasticity that prevents the bones from becoming brittle; proteoglycans help absorb and retain water in the matrix, making the bones resistant to compression.

The inorganic matrix is mainly composed of calcium phosphate, which combines with calcium hydroxide to form hydroxyapatite crystals.

These crystals form in between and around the triple-helical collagen fibrils, conferring hardness to the bone tissue.

Arrays of such mineralized fibrils form the collagen fibers that are arranged parallelly in the lamellae of the bone.

Thus, the different bone matrix components together form a hard tissue that can withstand both compressive and tensile forces.