The cell that builds new bone—it lays down the mineral matrix that makes bone hard and strong.Osteoblasts are bone-forming cells derived from mesenchymal stem cells. They synthesize and secrete osteoid (unmineralized bone matrix composed primarily of type I collagen), which subsequently mineralizes with hydroxyapatite crystals. Osteoblast activity is stimulated by PTH (intermittent exposure), PTHrP, and mechanical loading. Teriparatide and abaloparatide exert their anabolic bone-building effects primarily by stimulating osteoblast differentiation and activity, increasing bone formation rate above resorption rate.