F-actin turnover is required for furrow invagination. (A) 1 mM Jasp, 2 mM LatA, or DMSO control were injected into GFP-Dlg embryos at cycle-13 early prophase (when furrow is ∼3 μm in length), and furrow invagination was followed over time at depths from −2 μm to −8 μm below the embryo surface. (B) The lengths of invaginating furrows (y axis) over time (x axis) after 1 mM Jasp or DMSO injections in A. (C) Quantification of results in A. Increases in furrow lengths (in micrometers) 8 min after Jasp (n = 5 embryos) or DMSO (n = 5 embryos) injections were analyzed. ***, P < 0.001. Error bars represent SEM. Bar, 10 μm.