Fig 1: Inhibition of NHEJ during meiotic maturation increases the incidence of MI arrest by activating SAC and aberrant kMT attachments. (A–D) GV oocytes exposed to ETP were matured with SCR7. After 8 h of culturing, oocytes at the MI stage were subjected to chromosome spreading. (A,C) Representative chromosome spreads of MI oocytes stained with Mad2 and BubR1 antibodies. Scale bar, 10 μm. (B,D) Quantification of Mad2 and BubR1 intensities normalized to ACA signals. (E) Quantification of ACA intensities from the experiments illustrated in panel A and C. (F) PBE rates of oocytes after AZ3146 treatment during meiotic maturation. Data in the graphs are presented as mean ± SEM from three independent experiments. **p < 0.001, ***p < 0.0001, ns, not significant. (G) Representative images of kMT attachments in MI oocytes. Scale bar, 10 μm. (H) Quantification of kMT attachments