Centrosomes are mispositioned along the apical–basal axis in obelus mutants. (A–D) Localization of microtubules (α-tubulin) and centrosomes (Cnn) in wild-type (WT) and obe¹/obe² mutant embryos. A single z plane at the level of the centrosomes is shown. (E) Centrosomes fail to dissociate from microtubules in obe mutants and remain embedded in cortical microtubule arrays. (F) The percentage of centrosomes that correctly relocalized laterally in stage 7 was strongly reduced in obe¹/obe² mutants. Boxes, 25–75th percentile. Whiskers, 5–95th percentile. Horizontal line, median. +, mean. Plot shows the distribution of mean values across embryos (24–43 cells analyzed per embryo in 6–10 embryos per genotype). ***, P < 0.0001 by unpaired t test. (G–L) Centrosomes in wild-type and obe¹/obe² mutant embryos shown in two planes at the level of the apical adherens junctions (Par-3) and 2 µm below the adherens junctions (neurotactin [Nrt]). (G–I) Wild-type centrosomes move basally and toward the center of the cell in stage 6. (J–L) In obe mutants, centrosomes fail to move basally and remain associated with adherens junctions. The obe¹/obe² mutant embryos were the progeny of obe¹/obe² females crossed to obe²/+ males. Anterior left, dorsal up. Bars, 10 µm.