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How do osteoblasts form new bone tissue?

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Internal structure of a human long bone — bone A long bone of the human body, showing a magnified cross section of the interior.

Osteoblasts are specialized cells responsible for the synthesis and mineralization of bone during both initial bone formation and bone remodeling.1

These cells originate from the differentiation of osteogenic cells located in the periosteum and the endosteum of the marrow cavity. To form new tissue, osteoblasts secrete a gelatinous organic matrix called osteoid, which consists primarily of collagen and other proteins.12

Following the secretion of osteoid, inorganic salts are deposited into the matrix to harden it into mineralized bone. As this material calcifies, the osteoblasts become trapped within small spaces known as lacunae. Once entrapped, these cells differentiate into osteocytes, or mature bone cells, which maintain communication with other cells through a network of channels called canaliculi. This entire process requires a consistent supply of blood to ensure proper cellular differentiation.21