Stable K-MT attachment is delayed until late in MI. Oocytes were cultured for 2.5 h after GVBD to prometaphase I or 6.5 h to MI, then analyzed for cold-stable MTs. (A) Images are projections of a confocal z series showing MTs (green), kinetochores (CREST, red), and DNA (blue). Individual kinetochores were classified as end-on attached (1), unattached (2), or lateral (3); insets are optical sections showing examples of each (bar, 0.5 µm). (B) The percent of kinetochores in each category was averaged over multiple cells (n ≥ 17, 15 kinetochores per cell) at each time point (*, P < 0.001).