ERK3 deletion arrested oocytes at the MI stage and led to decreased spindle stability.

<p>After microinjection of ERK3 MO, the oocytes were incubated in M2 medium containing 2.5 µM milrinone for 21 h, then transferred to milrinone-free M2 medium for 10 h. (A) Western blot of ERK3 in the ERK3 MO group and control group. The ERK3 molecular mass is 100 kDa and that of actin is 42 kDa. (B) Relative intensity of ERK3/β-actin was assessed by volume analysis. (C) After microinjection, oocytes microinjected with ERK3 morpholino were arrested at the MI stage at 10 h of culture, but the control oocytes were in the AI stage. Double staining of α-tubulin (green) and DNA (red). Bar = 10 µm. (D) Percentage of oocytes in the ERK3 MO microinjected group (n = 42) and control group (n = 40). Data are presented as mean ± SE. Different superscripts indicate statistical difference (p<0.05). (E) Percentage of oocytes with abnormal spindles in the ERK3 MO injected group (n = 45) and control group (n = 44). (F) Percentage of oocytes with misaligened chromosomes in the ERK3 MO injected group (n = 45) and control morpholino injected group (n = 44). Data are presented as mean ± SE. Different superscripts indicate statistical difference (p<0.05).