Springer Online Journal Archives 1860-2000
Abstract Transparent hydroxyapatite (HA), 99.6% relative density, was prepared by hot isostatic pressing. Optical transmittance of 1 mm thick HA was greater than 60% at 700 nm. Twenty transparent HA plates (10×7×1 mm) were implanted into the medullary cavities of two dogs' femora. At 1 and 2 weeks after implantation the bone marrow derived cells that adhered to the HA surfaces were histochemically examined by light microscopy and scanning electron microscopy. Four types of enzymatic reactions were employed to identify cell types. Alkaline phosphatase was used as a marker for osteoblasts, acid phosphatase and tartrate-resistant acid phosphatase as a marker for osteoclasts and non-specific esterase as a marker for macrophages. Cells adhered to the HA surfaces were a mixed population of osteoblasts, osteoclasts and macrophages. By 2 weeks, the number of osteoblasts increased and formed a bone-like matrix. A small number of osteoclasts formed resorption lacunae on the HA after 2 weeks. By utilizing the transparency of the HA, whole-view of bone matrix formation by osteoblasts and simultaneous resorption of HA by osteoclasts was observed simply and dynamically by light microscopy.
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