What cell type is primarily responsible for bone formation?

What cell type is primarily responsible for bone formation?

• A. Osteocytes
• B. Osteoblasts
• C. Osteoclasts
• D. Chondrocytes

Answer: (B)

Osteoblasts are the cells responsible for forming bone. They come from mesenchymal stem cells and work on bone surfaces to synthesize and secrete the osteoid, the unmineralized protein matrix mainly made of collagen type I and other non-collagenous proteins. This matrix then mineralizes with calcium phosphate to become bone tissue. As osteoblasts lay down new matrix, many stay on the surface to continue forming bone, while some become embedded in the matrix and differentiate into osteocytes, the mature bone cells that maintain bone tissue. In contrast, osteoclasts resorb bone, and chondrocytes produce cartilage rather than bone (bone can form from cartilage in endochondral ossification, but the actual builders of the bone matrix are the osteoblasts). So the primary cell type driving bone formation is the osteoblast.

Osteoblasts are the cells responsible for forming bone. They come from mesenchymal stem cells and work on bone surfaces to synthesize and secrete the osteoid, the unmineralized protein matrix mainly made of collagen type I and other non-collagenous proteins. This matrix then mineralizes with calcium phosphate to become bone tissue. As osteoblasts lay down new matrix, many stay on the surface to continue forming bone, while some become embedded in the matrix and differentiate into osteocytes, the mature bone cells that maintain bone tissue. In contrast, osteoclasts resorb bone, and chondrocytes produce cartilage rather than bone (bone can form from cartilage in endochondral ossification, but the actual builders of the bone matrix are the osteoblasts). So the primary cell type driving bone formation is the osteoblast.