Which cell type manufactures and secretes proteins that form a mineralizable bone matrix?

Which cell type manufactures and secretes proteins that form a mineralizable bone matrix?

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

Answer: (C)

This question tests understanding of which bone cell makes and secretes the organic matrix that later becomes mineralized. Osteoblasts are the cells that synthesize the organic component of bone, the osteoid, which includes type I collagen and various noncollagenous proteins. They secrete this matrix onto existing bone surfaces and release minerals that infiltrate the matrix to form hydroxyapatite, transforming the osteoid into hardened bone. Osteoblasts originate from mesenchymal stem cells and line the bone surface during formation; when they become embedded in the matrix, they differentiate into osteocytes, which are mature, non-secreting cells. Osteoclasts, by contrast, resorb bone tissue, not form it. Chondrocytes produce cartilage matrix, not bone matrix, and are involved in cartilage formation rather than mineralized bone formation directly. The key idea is that the mineralizable bone matrix is produced by osteoblasts, setting the stage for bone mineralization.

This question tests understanding of which bone cell makes and secretes the organic matrix that later becomes mineralized. Osteoblasts are the cells that synthesize the organic component of bone, the osteoid, which includes type I collagen and various noncollagenous proteins. They secrete this matrix onto existing bone surfaces and release minerals that infiltrate the matrix to form hydroxyapatite, transforming the osteoid into hardened bone. Osteoblasts originate from mesenchymal stem cells and line the bone surface during formation; when they become embedded in the matrix, they differentiate into osteocytes, which are mature, non-secreting cells.

Osteoclasts, by contrast, resorb bone tissue, not form it. Chondrocytes produce cartilage matrix, not bone matrix, and are involved in cartilage formation rather than mineralized bone formation directly. The key idea is that the mineralizable bone matrix is produced by osteoblasts, setting the stage for bone mineralization.