Abstract: 【Objective】 In order to explore the protective effect of antifreeze protein Ⅲ (AFP Ⅲ) on mitochondria of vitrified mouse oocytes. 【Method】 Kunming female mice aged 5-8 weeks were used as test materials,the collected mouse oocytes at MⅡ stage were randomly divided into blank control group,frozen control group and AFP Ⅲ adding group (500 ng/mL AFP Ⅲ was added to frozen balance solution and frozen solution),Mito-Tracker green (MTG) was used to detect the distribution and content of mitochondria,JC-1 fluorescence staining was used to detect mitochondrial membrane potential,Lyso-Tracker red (LTR) was used to detect the co-localization of mitochondria and lysosomes,dichlorofluorescein diacetic acid (DCFH-DA) was used to detect the level of ROS,and ATP Assay Kit was used to detect the content of mitochondrial ATP.【Result】 Compared with the blank control group,the content of mitochondria in mouse oocytes were decreased significantly after vitrification,some mitochondria showed abnormal scattered distribution,the co-localization of mitochondria and lysosomes were increased,and the mitochondrial membrane potential was decreased significantly (P＜0.05).Compared with the frozen control group,the mitochondrial content of mouse oocytes in AFP Ⅲ group was significantly increased,the abnormal distribution of mitochondria and the co-localization of mitochondria lysosomes were reduced,and the mitochondrial membrane potential was significantly increased (P＜0.05).Compared with the blank control group,the ROS content of mouse oocytes was significantly increased and ATP content was significantly decreased after vitrification (P＜0.05). Compared with the frozen control group,the ROS content of AFP Ⅲ group was significantly decreased and ATP content was significantly increased (P＜0.05).【Conclusion】 AFP Ⅲ could improve the oxidative stress response of vitrified mouse oocytes and protect mitochondria of frozen and thawed oocytes.

Key words: antifreeze protein Ⅲ (AFP Ⅲ); mitochondrion; oocyte; vitrification