Timelapse of dorsal yolk syncytial layer (YSL) nuclei and blastoderm morphogenesis from sphere stage (late blastula) to 1 somite stage. Top panel shows Nomarski movie of blastoderm morphogenesis including epiboly, gastrulation, convergence and extension, and notocord formation. Bottom panel show a confocal projection view of YSL nuclear movements including nuclear divisions, epiboly movements, and convergence and extension. Notice how some YSL nuclei that are located at the dorsal margin extend along the entire dorsal axis. Sphere is approximately 700 microns in diameter. Video made available through Mark Cooper and Zebrafish The Living Laboratory.