A researcher tags osteocytes in cortical bone of a young adult mouse and follows their fate. Osteocytes are terminally differentiated cells derived from osteoblasts that became entombed in matrix. Which property best describes their role in bone homeostasis?
- A They form mechanosensory network via canaliculi and regulate osteoblast and osteoclast activity through sclerostin and RANKL signaling ✓
- B They resorb bone directly using ruffled borders facing Howship lacunae
- C They secrete osteoid seams that subsequently mineralize under PTH stimulation
- D They line quiescent bone surfaces and exchange calcium with blood through gap junctions alone
Correct answer: A. They form mechanosensory network via canaliculi and regulate osteoblast and osteoclast activity through sclerostin and RANKL signaling
Explanation
Osteocytes sit in lacunae and communicate through canaliculi containing slender cytoplasmic processes joined by gap junctions. They function as mechanosensors and secrete sclerostin (SOST) to inhibit osteoblast activity and express RANKL to support osteoclastogenesis. Ruffled borders belong to osteoclasts, and active osteoid secretion belongs to osteoblasts.
Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.
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Written and medically reviewed by the StethoPrep medical team.