Global comparative transcriptome analysis of cartilage formation in vivo

We set out to characterize the gene expression changes which take place during chondrogenesis in the developing mouse limb. RNA derived from pre-condensed mesenchyme, mesenchymal condensations, and cartilage anlagen representing the earliest stages of tibial and fibular development was analysed by whole genome microarray analysis, and revealed 931 genes differentially expressed in these tissues. Among them were 892 genes not previously identified during the initation of chondrogenesis, including members of the Bmp, Wnt, Gdf, Sox, and Fox gene families. These microarray data were validated by qPCR, in situ hybridisation, and analysis of numerous genes already implicated in chondrogenesis in the scientific literature. 231 sections from a total of four 11.5dpc mouse hind limbs, three 12.5dpc mouse hind limbs, and four 13.5dpc mouse hind limbs (all from separate mice) were microdissected, and tissues from each time point were pooled. Thus, this experiment consisted of one replicate only.