Which of the following cells lines the surface of bones and are former osteoblasts?

• A. Osteocytes
• B. Osteoblasts
• C. Osteoclasts
• D. Lining cells

Answer: (D)

The cells that line the surface of bones and are former osteoblasts are known as lining cells. Lining cells represent a differentiated form of osteoblasts that have lost their active bone-forming function. Instead, they play a supportive role in maintaining the bone matrix and regulating the exchange of ions and nutrients between the bone surface and surrounding tissues.

Lining cells are important for bone remodeling as they help to protect the underlying bone from resorption and aid in the process of bone repair. They help to control the activity of osteoclasts (the cells responsible for bone resorption) and can become active osteoblasts again when there is a need for new bone formation.

Understanding the role of lining cells is crucial in the context of bone health, remodeling, and disorders that affect bone density. Hence, recognizing that these cells are derived from osteoblasts and their function is vital in bone biology reinforces the importance of proper cell identification in the study of bone densitometry and overall skeletal health.