Phagocytosis of osteocytes by osteoclasts in femora of two week-old rabbits.

The osteoclast-osteocyte relationship at the endosteal surface of femora of two-week old rabbits was studied. Light microscopic observations suggest that during physiological resorption phagocytosis by osteoclasts of osteocytes takes place. Serial sections confirm that the cells are totally engulfed within the cytoplasm of the osteoclasts. Ultrastructural studies support these findings and indicate that the initial stage of phagocytosis of the osteocytes consists of the insinuation of an extnesion of the ruffled border into the osteocyte lacuna. These extensions are seen to make close contact with the osteocytes prior to their engulfment by the osteoclasts and their final digestion within phagosomes.