Initiation of endochondral calcification is related to changes in the redox state of hypertrophic chondrocytes.
The level of pyridine nucleotides (NADH and NAD+) in the mineralizing growth plate of the chick was ascertained by high-resolution scanning microfluorimetry and biochemical analysis. Scanning electron microscopy and light microscopy were used to relate the concentrations of NADH and NAD+ to stages of chondrocyte maturation. A dramatic increase was found in the relative concentration of reduced pyridine nucleotides in the hypertrophic zone. On either side of this zone, in proliferating and calcifying cartilage, there was a decrease in NADH fluorescence, and the NADH/NAD+ ratio was depressed. The finding that NADH accumulated in the tissue zone associated with the earliest deposition of bone mineral supports the hypothesis that a change in the redox state initiates tissue mineralization.
D000818:Animals; D001846:Bone Development; D002118:Calcium / Q000378:metabolism*; D002356:Cartilage / Q000502:physiology*; D002645:Chickens; D004838:Epiphyses / Q000502:physiology / Q000648:ultrastructure; D008903:Minerals / Q000378:metabolism; D008928:Mitochondria / Q000378:metabolism; D009243:NAD / Q000378:metabolism*; D010084:Oxidation-Reduction; D010101:Oxygen Consumption
D008903:Minerals; D009243:NAD; D002118:Calcium