[Structural modifications of medullary bone osteoclasts during a hypocalcemic diet].

The medullary bone of laying hens after seven days of hypocalcaemic diet has been investigated with the aim of analyzing the fate of osteoclasts, very numerous in the first days of the diet and after substituted on the trabecular surfaces by active osteoblasts. The first observations show that there is a marked change in the osteoclasts ultrastructure. Large amount of endoplasmic granular reticulum in regular rows are accumulated at the cell periphery. Cytoplasmatic blebs, microvilli and laminae ondulantes are visible on the cell surfaces. Mononuclear cells with variable amount of cytoplasm rich in organuli are detached from osteoclasts. The ultrastructure and the fate of this elements are discussed.