Aurora B/C kinase activity and tension regulate K-MT attachments during meiosis I. (A and B) Oocytes were cultured for 5.5 h after GVBD, then treated with Aurora B/C inhibitor ZM447439 or DMSO (control) for 1 h before analysis of cold-stable MTs. (C and D) Oocytes injected with AA-separase cRNA together with securin MO, or GFP cRNA as a control, were matured for 6.5 h after GVBD, then analyzed for cold-stable MTs. (E and F) Oocytes injected with AA-separase cRNA and securin MO were cultured for 5.5 h after GVBD, then treated with ZM447439 (or DMSO) for 1 h before analyzing cold-stable MTs. Only oocytes with complete chromatid separation were analyzed, indicating loss of cohesion. Images (A, C, and E) are projections of a confocal z series showing MTs (green), kinetochores (CREST, red), and DNA (blue). Insets in C are optical sections showing lateral interactions (bar, 0.5 µm). Percentages of end-on attached, unattached, and lateral kinetochores were averaged over multiple cells (n ≥ 13, ≥15 kinetochores per cell; *, P < 0.001).