The process by which bone forms from a cartilage template is called?

• A. Intramembranous ossification
• B. Osteogenesis imperfecta
• C. Hematopoiesis
• D. Endochondral ossification

Answer: (D)

Endochondral ossification is the process by which bone forms from a cartilage template. In this pathway, a hyaline cartilage model serves as the scaffold that is gradually replaced by bone tissue, which is how most long bones grow in length and develop through primary and secondary ossification centers. Chondrocytes proliferate and enlarge, the cartilage matrix calcifies, and blood vessels invade, bringing in osteoblasts to lay down bone.

In contrast, intramembranous ossification forms bone directly from mesenchymal tissue without a cartilage stage, as seen in some flat bones like the skull. Osteogenesis imperfecta is a genetic disorder affecting bone quality, not the process of bone formation from cartilage. Hematopoiesis is the production of blood cells in bone marrow, not bone formation.