Which cells are precursor cells in bone formation that form bone tissue?

• A. Osteoblasts
• B. Endosteal cells
• C. Osteocytes
• D. Fibroblasts

Answer: (A)

Bone formation begins with osteoblasts, the precursor cells that actively form bone tissue. Derived from mesenchymal stem cells, osteoblasts synthesize the organic matrix of bone (the osteoid), rich in type I collagen and non-collagenous proteins, and they promote mineralization by secreting enzymes like alkaline phosphatase. As the matrix hardens, some osteoblasts become embedded and mature into osteocytes, which reside in lacunae and maintain bone. Endosteal cells line inner bone surfaces but don’t initiate bone formation, fibroblasts produce connective tissue rather than bone, and osteocytes are mature bone cells, not the forming precursors. So the cells responsible for forming bone tissue are osteoblasts.