Wapl depletion causes severe chromosome segregation defects in old oocytes. (A) Representative stills of high-resolution live-cell imaging videos showing chromosome segregation in Wapl^fl/fl and Wapl^Δ/Δ oocytes isolated from 14-mo-old females. DNA is shown in magenta and centromeres (CENP-C) in green. White arrowheads indicate chromosome bridges, lagging chromosomes or misaligned chromosomes. The time displayed indicates hours after GV breakdown. Scale is the same in all images; scale bar, 10 µm. (B) Quantification of chromosome segregation defects observed in live-cell imaging videos of Wapl^fl/fl and Wapl^Δ/Δ oocytes isolated from 14-mo-old females. The number of oocytes analyzed is indicated in the figure. (C) Representative images of metaphase II spreads of Wapl^fl/fl and Wapl^Δ/Δ oocytes isolated from 14-mo-old females. Centromeres are shown in red and DNA in blue. The white arrowheads show single chromatids, which are highlighted in inset magnifications. Scale is the same in all images; scale bar, 5 µm. Inset scale bar, 5 µm. (D) The number of dyads was quantified in metaphase II chromosome spreads of Wapl^fl/fl and Wapl^Δ/Δ oocytes isolated from 14-mo-old females. The metaphase II chromosome spreads were classified in euploid (20 dyads), hyperploid (>20 dyads), and PSSCs. Four Wapl^fl/fl and four Wapl^fl/fl (Tg)Zp3-Cre littermate females were analyzed, and the total number of oocytes analyzed is indicated in the figure.