Fig 1. The formin inhibitor SMIFH2 blocks mouse oocyte maturation.

A. Treatment with SMIFH2 decreases the oocyte maturation rate and increases the ratio of symmetric division. SMIFH2 was added to M16 culture medium at concentrations of 0, 100, 200, 300, 400, and 500 μM and immature oocytes were cultured for 12 h after which their status of development was assessed. At least 3 independent experiments were carried out and the ratios of oocytes at each developmental stage to total oocytes were plotted. Significant differences (p < 0.05) between the treated groups are indicated by a different superscript letters(a,b,c,d and e). B. Representative pictures of oocytes treated with SMIFH2. White arrows indicate abnormally matured oocytes, while black arrows mark oocytes that failed to mature at the MII stage after 12 h of growth. C: Treatment with SMIFH2 for distinct durations and the effect thereof on oocyte maturation. CON: control group without SMIFH2 treatment; 0–12: the oocytes were treated with 500 μM of SMIFH2 during the entire incubation time; 0–2, 0–4, 0–8: the oocytes were treated with 500 μM of SMIFH2 during 0–2, 0–4, and 0–8 h after the start of incubation, respectively, and then transferred to fresh M16 medium without SMIFH2; 4–12, 8–12: the oocytes were cultured without SMIFH2 for 4 and 8 h, respectively, after which 500 μM of SMIFH2 was added to the medium. Maturation ratios after 12 h of incubation for each treatment group are plotted. Statistical differences (p < 0.05) between different treatments are indicated by a different superscript letters(a,b,c,d and e).