3-D Movies of Zebrafish Gastrulation:
Shield formation at 60%.
Cells in the shield region move deeper into the hypoblast of shield and move toward the animal pole. Involution-like movment of cells in lateral regions.
Shield formation movie: The animal pole is toward the top, face on view of dorsal side (shield region).
Scatter labeling of cells with the flourescent probe, Bodipy-dextran, allows many individual cells to be followed through time. Notice the cells at the far left of the image: they undergo an involution-like movement from the surface (epiblast) into a deeper position (hypoblast) and then move away from the margin. Cells in the shield region appear to be undergoing a similar movement into the shield hypoblast and then toward the animal pole. NEM/forerunner cells are visible as labeled cells collecting at the margin near the right edge of the image. They do not involute as other cells underneath them are diving into the hypoblast. Remember, not all of the cells are labeled in the embryo; the holes that you see between the cells are filled with cells that are not labeled with the flourescent probe.