Figure 1. Graphical depiction of how the segmentation of the presomitic mesoderm leads to the formation of the axial myotome. (A) The oscillation of Notch-Delta genes leads to the segmentation of the presomitic mesoderm into somites. The 3 somite stage is shown. (B) The somites are transient structures with a chevron shape in the paraxial mesoderm of the zebrafish embryo, and will generate the axial muscles and later aspects of the vertebrae. (C) The adult zebrafish musculature presents the same segmental periodicity as the embryonic somites.