Epithelial Cells Exhibit Dynamic Filopodia During Zebrafish Epiboly

Initially, the zebrafish embryo consists of a cell mass (blastoderm) atop a large yolk cell. During gastrulation, epiboly is the process whereby the blastoderm thins and spreads downwards to enclose the yolk. The blastoderm comprises an outer epithelium, the enveloping layer (EVL), and inner deep cells (DCs). The EVL stretches during epiboly, while the DCs undergo cell rearrangements. I observed cellular protrusions between EVL and DCs and investigated their potential role in facilitating epiboly. I classified the protrusions as filopodia by using actin markers and examined their spatio-temporal dynamics by live imaging. Filopodia were found throughout the EVL and in the largest number during early epiboly at the animal pole, where DC rearrangements are greatest. In functional studies, expression of a constitutively active actin bundling protein resulted in increased EVL filopodial length and delayed epiboly. These results suggest that EVL filopodia may function during early epiboly to promote DC rearrangements.M.Sc.2020-11-15 00:00:0