The effects of lanthanum on the ultrastructure of hypertrophic chondrocytes and the localization of lanthanum precipitates in condylar cartilages of rats fed on normal and rachitogenic diets.
Ionic lanthanum was used to examine the distribution of calcium-binding sites in the condylar cartilages of rats that had been fed on normal and/or vitamin D-deficient rachitogenic diets for 4 weeks. Certain specific changes in the ultrastructure of the cartilage were attributed to the presence of the trivalent cation in the fixation medium. Cartilages from the rachitic animals showed a marked reduction in the quantity of lanthanum deposition on the outer surface of the chondrocytes and in the extracellular matrix. Returning rachitic rats to the control diet resulted in a corresponding return to a normal ultrastructural distribution of lanthanum in the condylar cartilages. No intracellular lanthanum deposits were observed. The results suggest that a vitamin D-dependent calcium-binding component may be an integral part of the chondrocyte plasma membrane structure.
D000818:Animals; D001665:Binding Sites; D002118:Calcium / Q000378:metabolism*; D002356:Cartilage / Q000378:metabolism* / Q000648:ultrastructure*; D002462:Cell Membrane / Q000378:metabolism / Q000648:ultrastructure; D006965:Hyperplasia; D007811:Lanthanum / Q000378:metabolism / Q000494:pharmacology*; D051381:Rats; D012279:Rickets / Q000378:metabolism* / Q000473:pathology; D014807:Vitamin D / Q000494:pharmacology
D014807:Vitamin D; D007811:Lanthanum; D002118:Calcium