Several non-bioriented bivalents fail to prevent APC activation in small oocytes. (A) Percentage of B₀ and B₃ oocytes extruding polar bodies with or without addition of 25 nM nocodazole to the culture medium. Statistical test was Fisher’s exact. Error bars indicate 95% confidence interval. (B) Representative time-lapse images of oocytes expressing H2B-mCherry and CenpC-GFP with time relative to anaphase. Bar, 10 µm. (C) Number of bivalents per oocyte classed as non-bioriented (>3 SDs from the control mean in any of the parameters of stretch, displacement, or θ) at times relative to anaphase. Statistical test is Dunn’s multiple comparison test; n.s. not significant; *, P < 0.05; **, P < 0.01. (D) 3D scatterplot of bivalents 5 min before anaphase in B₃ oocytes cultured in 25 nM nocodazole. Colors indicate the number of SDs a bivalent is, according to its worst-performing measure, from mean values defined by metaphase oocytes treated without nocodazole (green <1, yellow ≤2, orange ≤3, and red >3). (E) Proportion of bivalents for B₀ oocytes falling within the stated number of SDs at anaphase −5 min.