A patient with osteopetrosis has defective osteoclast function. On electron microscopy, normal osteoclasts exhibit a specialized ruffled border adjacent to bone matrix. What is the primary function of this ruffled border?
- A Synthesis and secretion of type I collagen
- B Formation of cement lines for structural support
- C Secretion of hydrogen ions and acid phosphatase to dissolve mineral ✓
- D Phagocytosis of apoptotic osteocytes
Correct answer: C. Secretion of hydrogen ions and acid phosphatase to dissolve mineral
Explanation
The ruffled border increases surface area for secretion of hydrogen ions and acid phosphatase to acidify the subosteoclastic compartment and dissolve hydroxyapatite. Collagen synthesis is performed by osteoblasts. Cement lines are formed during the reversal phase of bone remodeling, not by the ruffled border.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.