Effect of alpha-linolenic acid (ALA; 50 μM) treatment on intra-oocyte GSH content during in vitro maturation of porcine oocytes. (A) Fluorescent microscopic images of porcine oocytes. (B) Fluorescence intensity of GSH levels. Scale bar: 200 μm. a-cDifferent superscripts indicate significant difference between 0 h, 22 h and 44 h after in vitro maturation (p < 0.05). Asterisks indicate differences between control group and ALA group at 22 h after in vitro maturation (p < 0.05).