[Multiparametric cytofluorometry of the process of cellular proliferation, differentiation and maturation of the chondrocytes in the growing rat].

The present study was undertaken to analyze quantitatively the process of cellular proliferation, differentiation and maturation of the chondrocytes in both the epiphyseal cartilage plates and the articular cartilages of the growing rats, using the multiparametric cytofluorometry (NIKON SPM-RFl-D). The analyses involve the simultaneous determinations by cytofluorometry of nuclear DNA vs. cellular RNA contents, nuclear DNA vs. cellular protein contents, and nuclear DNA vs. silver grain amount of the 3H-leucine, 3H-glycine, 3H-thymidine and the 35SO4 autoradiography. In addition, for the detailed analysis of cell kinetics, DNA-RNA cytofluorometry was carried out in combination with 3H-thymidine autoradiography. According to the results obtained, the chondrocytes were quantitatively divided into subpopulations of G0-G1, S and G2 in the cell cycle by their nuclear DNA and cellular RNA contents, and the maturative chondrocytes had higher cellular RNA content than the proliferative ones. It was suggested that there were, among the chondrocytes in the epiphyseal cartilage plate, two other subpopulations of binuclear cells and mononuclear tetraploid cells, both having higher cellular RNA content than the mononuclear G2 cells. It is reasonable to assume that these two subpopulations are the polyploid cell groups accompanying highly active cell proliferation.