cdc-42 embryos have defects in ventral enclosure and elongation. (A) Stages of embryo elongation: bean stage (pre-elongation), comma stage (1.4-fold), and pretzel stage (>3-fold). Junctions between epidermal cells are indicated with black lines. Lateral epidermal cells (“seam” cells) are yellow. Double-headed arrows indicate the extension in anterior-posterior length of a cell as the embryo elongates. (B and C) Stills from DIC time-lapse movies of control and cdc-42(MZ) embryos shown at 30-min intervals. Genotypes were confirmed by single-embryo PCR after imaging. Arrows in C point to extruding cells. See Video 1. (D) Phenotypic classes of arrested embryos from DIC time-lapse imaging experiments (n = 39). (E) Rates of elongation in control (n = 13) and Class III (n = 9) embryos. Fold elongation was measured as schematized. t = 0 represents the comma stage. Values are the mean ± SD. Data for D and E were pooled from eight independent imaging experiments. P-values were calculated using a Mann-Whitney U test. ***, P ≤ 0.001. Bars, 5 µm.