EXPRESSION OF VIGILIN IN CHICKEN CARTILAGE AND BONE

The expression of vigilin was followed during chick embryonal developm ent by in situ hybridization. Vigilin mRNA is abundantly expressed in tissues of mesenchymal and ectomesenchymal origin. The mesenchymal pri mordial cells of cartilage and bone did not show any significant expre ssion of vigilin. As tissue differentiation proceeded, vigilin mRNA le vels increased in hyaline cartilage and in both endochondral as well a s intramembranous bone. The results suggest that the expression of vig ilin mRNA in cartilage- and bone-forming cells, chondrocytes and osteo blasts, is dependent on the stage of development and cellular differen tiation, although not a unique process of bone formation. Most strikin g is the correlation of the maximum vigilin mRNA expression in osteobl asts and hypertrophic chondrocytes to periods when cell-specific genes were highly transcribed and substantially translated, e.g., synthesis of procollagen and formation of extracellular matrix in bone and cart ilage.