Which phase of the bone remodeling cycle involves osteoclasts forming on the bone surface?

• A. Activation
• B. Resorption
• C. Reversal
• D. Formation

Answer: (A)

The correct phase of the bone remodeling cycle where osteoclasts form on the bone surface is the activation phase. During this phase, signaling molecules, such as RANKL (Receptor Activator of Nuclear factor Kappa-Β Ligand), stimulate the differentiation of osteoclast precursors into mature osteoclasts. These osteoclasts attach to the bone surface, preparing for their role in bone resorption.

In this context, the activation phase is crucial as it initiates the remodeling process. It sets the stage for subsequent activities by mobilizing osteoclasts to areas where bone needs to be resorbed. Understanding this phase is essential for comprehending how bone is maintained and remodeled throughout life in response to various physiological demands, aging, and other factors.