A bone biopsy from a patient with severe hyperparathyroidism shows numerous multinucleated cells located in shallow depressions on the bone surface. What are these resorption bays called, and what is the specific ultrastructural feature of these cells that increases their surface area for resorption?

• A Howship's lacunae; ruffled border ✓
• B Haversian canals; ruffled border
• C Volkmann's canals; clear zone
• D Howship's lacunae; clear zone

Explanation

Howship's lacunae are the resorption bays where osteoclasts attach to bone. The osteoclast develops a ruffled border to increase surface area for secreting acid and enzymes. Haversian and Volkmann's canals are vascular channels, not resorption bays. The clear zone seals off the resorption site but does not increase surface area.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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