Reducing actin depolymerization by tsr or promoting actin polymerization by Jasp ameliorates the furrow defects observed in nuf embryos. (A) Green, GFP-Moesin; Red, tubulin. Compared with nuf¹ embryos (top row, the same embryo as shown in Fig. 4 A), tsr¹/Cy; nuf¹ embryos (bottom row) exhibited normal furrow structures from interphase to metaphase during cycle 13. For full movie, see Video 5 . (B) Quantifications of results in A and C. At metaphase cycle 13, furrow break index and spindle fusion index in nuf¹ (N = 12 and n = 1,378), tsr¹/Cy; nuf¹ (N = 8 and n = 1,010), and nuf¹ + Jasp (N = 7 and n = 846) embryos. N, total embryos examined; n, total nuclei/mitotic spindles analyzed. **, P < 0.01; ***, P < 0.001. Error bars represent SEM. (C and D) nuf¹ embryos expressing GFP-Dlg were injected with either 1 mM Jasp or DMSO at cycle-13 early prophase. (C) Jasp-injected nuf embryos show very few furrow breaks at metaphase, whereas DMSO-injected nuf embryos display extensive discontinuous furrows resulting from progressive loss of furrow membrane (arrows). See Videos 6 and 7 . (D) The membrane loss before Jasp injection in nuf¹ embryos was not compensated after Jasp treatment (arrows). Bars: (A and D) 10 μm; (C) 20 μm.