Effects of metformin (Met) on the meiotic maturation in the arecoline (Are)‐exposed oocytes. A, Experimental process overview. B, Representative images of oocytes after 12 h of culture were treated with Are. C, The rates of first polar body extrusion after Are treatment. D, Representative images of oocytes in the control, Are and Are + Met groups. E, The rates of first polar body extrusion in the control, Are and Are + Met groups. F, The rates of germinal vesicle breakdown. Scale bar = 100 μm. White arrow shows the MII stage oocyte with the first polar body, and yellow arrowhead shows the oocyte that has undergone apoptosis. Data were presented as mean ± SD. a‐cMeans not sharing a common superscript are different (P < .05)