Since Solursh and his coworkers set up the limb bud micromass cultures in 1977 (1 ), this procedure has become a major model to analyze cellular and molecular event involved in chondrogenesis (2 –7 ). Recently, RCAS retroviral vectors have been developed that can infect chicken embryosin ovo. These have advanced our understanding in limb bud patterning remarkably (8 ). Here we describe a newly developed protocol to merge these two procedures, which will make micromass culture an even more powerful model for the analysis of chondrogenic mechanisms.
