Tg(sox17:GFP-UTRN) expression labels actin-based structures in endodermal cells. (A–C) Images were taken from lateral marginal regions of gastrulating zebrafish embryos (6–9 h after fertilization). (A and B) Fluorescence from Tg(sox17:GFP-UTRN) expression accumulates in actin-based structures such as lamellipodia (arrow in A) and retraction fibers (arrowhead in A) as well as cytokinetic furrows (arrow in B). (C) More detailed actin organization including actin bundles can be seen at higher magnification. Bars, 10 µm.