Abstract: To investigate the effect of mitochondrial transfer (MIT) of aging mouse oocytes on the mitochondrial membrane potential (△Ψm) of the subsequent preimplantation embryos. MethodsSixto eightweek old female KM BAI mice were superovulated, and the oocytes retrieved were treated by intracytoplasmic sperm injection (ICSI) and medium blank injection. The subsequent embryos were distributed in group A. Twelve months old female KM BAI mice were superovulated and the oocytes obtained were divided into two subsets. One was treated by ICSI and medium blank injection and the subsequent embryos were included in group B, the other was treated by ICSI and MIT and the subsequent embryos were included in group C. Comparisons were performed on △Ψm among the three groups during the preimplantation stages and on the alterations of △Ψm across the preimplantation stages of each group. ResultsAt the 2cell stage and morula stage, △Ψm of embryos from groups A and C were higher than those from group B (P＜0.01), while at the 4cell stage, 8cell stage and blastocyst stage, △Ψm of embryos from groups A and C were also higher than those from group B (P＜0.05). In all of the three groups, △Ψm of embryos at either the morula stage or blastocyst stage was higher than those at any other cleavage stage (P＜0.05), while there were no significant differences between the morula stage and blastocyst stage and also no significant differences among the cleavage stages. ConclusionThe MIT of aging mouse oocytes can significantly improve the B△Ψm of subsequent preimplantation embryos