Giant, multinucleate cells derived from hematopoietic stem cells that resorb bone.

• A. Osteogenic Cells
• B. Osteoblasts
• C. Osteocytes
• D. Osteoclasts

Answer: (D)

This describes osteoclasts. The key idea is that bone resorption is carried out by specialized cells that come from the hematopoietic lineage. Osteoclasts are large and multinucleated, formed by the fusion of multiple monocytes, which is why they appear as giant cells. They attach to the bone surface and create a sealed, acidic environment, releasing enzymes that dissolve both the mineral and organic components of bone. This resorption is a normal part of bone remodeling and helps regulate calcium levels.

Other bone cells have different roles and origins: osteoblasts form new bone and come from mesenchymal stem cells; osteocytes are mature osteoblasts embedded in bone matrix that help coordinate remodeling; osteogenic (osteoprogenitor) cells are the stem-like cells on the periosteum and endosteum that can become osteoblasts. So the combination of multinucleated origin from hematopoietic stem cells and bone-resorbing function points to osteoclasts.