Morphogenesis of the ventral yolk syncytial layer (YSL) from sphere stage to the end of gastrulation. The last round of nuclear division occurs before marginal band contraction and epiboly begins. As convergence occurs toward the dorsal side, a divergence of YSL nuclei from the ventral midline can be seen in this timelapse. As nuclei on the dorsal side extend up and through the animal pole, animal pole nuclei move ventrally and laterally. Video made available by Mark Cooper through Zebrafish - The Living Laboratory.