Deletion of ERK3 induced unstable microtubule-chromosome attachments at the MI stage.

<p>(A) Oocytes of control and ERK3 MO groups were cultured for 8.5 h followed by cold treatment for 10 minutes in M2 medium which was pre-cooled at 4°C. Magnifications of the boxed regions show that all chromosomes were attached to microtubules in control oocytes, but not in ERK3 MO microinjected oocytes, whereas abnormal spindles were observed in ERK3 MO group. Bar = 10 µm. (B) Percentage of oocytes with normal spindles in the ERK3 MO group (n = 50) and control group (n = 49). Data are presented as mean ± SE. Different superscripts indicate statistical difference (p<0.05). Bar = 10 µm.