ES cell-derived presomitic mesoderm-like tissues for analysis of synchronized oscillations in the segmentation clock.

Somites are periodically formed by segmentation of the anterior parts of the presomitic mesoderm (PSM). In the mouse embryo, this periodicity is controlled by the segmentation clock gene , which exhibits wave-like oscillatory expression in the PSM. Despite intensive studies, the exact mechanism of such synchronous oscillatory dynamics of expression still remains to be analyzed. Detailed analysis of the segmentation clock has been hampered because it requires the use of live embryos, and establishment of an culture system would facilitate such analyses. Here, we established a simple and efficient method to generate mouse ES cell-derived PSM-like tissues, in which expression oscillates like traveling waves. In these tissues, oscillation is synchronized between neighboring cells, and the posterior-anterior axis is self-organized as the central-peripheral axis. This method is applicable to chemical-library screening and will facilitate the analysis of the molecular nature of the segmentation clock.