抄録
We examined cell kinetics of bone cells and chondrocytes in the femur of young growing rats using flash and cumulative labeling with bromodeoxyuridine (BrdU). As flash labeling, rats received an intravenous injection of BrdU. As cumulative labeling, rats were implanted with osmotic pumps filled with BrdU into the peritoneal cavity. The BrdU-labeled nuclei were immunohistochemically identified in decalcified paraffin-embedded specimens using anti-BrdU antibody. In the articular cartilage, BrdU-positive chondrocytes were observed in the middle of the cartilage by flash labeling, and the positive cells were constantly increased with the cumulative labeling days. In the growth plate, BrdU-positive chondrocytes were observed in the proliferating zone by flash labeling, and almost all chondrocytes were positive for BrdU by cumulative labeling. In the bone tissues, by flash labeling, the undifferentiated mesenchymal cells which seem to be a source of osteoblast were positively stained for BrdU. By cumulative labeling, BrdU-positive osteoblasts, osteocytes, and osteoclasts were observed and these cells were mainly localized in the metaphysis. The results suggest that the technique using the combination of flash and cumulative labeling the BrdU is useful for analysis of cell kinetics of bone cells and chondrocytes, and will be applicable to the analysis of bone and cartilage changes induced by various compounds and observed in animal models of skeletal diseases.
