Fig. 1.

Gene expression analysis of the chondrocytes isolated from developing rat epiphyseal heads. a Expression of the tenascin C gene (tnc), a typical marker of articular chondrocytes. The tnc mRNA levels in the chondrocytes in primary cell cultures and in those after 2 rounds of passages were quantified by real-time RT-PCR. RNA extracted from rat muscle tissue was used as a negative control. Data are presented as relative values against those of the glyceraldehyde 3-dehydrogenase gene (gapdh). b Strong expression of ccn3 in primary cultures of chondrocytes prepared from the epiphyseal heads. Messenger RNA expression levels of ccn3 and tnc genes were standardized against that expression level of the gapdh gene. Note that ccn3 mRNA showed even remarkably higher levels of expression than the housekeeping (gapdh) or articular chondrocyte marker (tenascin C: tnc) gene