Fig. 1

Fig. 1 Fluid-to-solid tissue transition during zebrafish posterior axis elongation. (a), Schematic lateral view of the zebrafish embryo at 10-somite stage, showing the previously reported² fluid-like mesodermal progenitor zone (MPZ) and solid-like presomitic mesoderm (PSM). (b), Cells from dorsal-medial (DM) tissues (green arrow) enter the ventral MPZ tissue at the posterior end (lateral view). The tissue undergoes a fluid-to-solid transition along the AP axis, as cells from the fluid-like MPZ mature and join the solid-like PSM. (c), Sketch of a dorsal view of ventral tissues showing both the fluid-to-solid tissue transition and the entrance of cells from the DM into the MPZ. (d–e), Spatial profiles of the rate of cell (material) addition to ventral tissues, Q(x) (d), and tissue viscosity, 𝜇(𝑥) (e), used in the simulations.