Due to the relevance of aging in infertility, methods to rejuvenate and improve oocyte quality have been developed. One of which is through Mitochondrial replacement therapies (MRTs). MESI is one of the heterologous total cytoplasmic transfer within MRTs where the spindle and its chromosomes (karyoplast) is transferred from a patient's oocyte (possessing poor mitochondrial quality) to the donor enucleated oocytes [1]. However, some ethical clearance and the future long-term effect of mtDNA heteroplasmy remain challenging, even though the percentage is less than 1% [2]. Another source of chromosomes to transfer is the polar body, which is relatively safe as it has fewer mitochondria than spindles and prokaryotes, enabling to reduction of the level of mtDNA carryover [3].
Photos are personal documentation.
References:
[1] Labarta et. al. 2019. Mitochondria as a tool for oocyte rejuvenation. Fertility and Sterility
[2] Ogawa et. al. 2020. Improvement of early developmental competence of postovulatory-aged oocytes using metaphase II spindle injection in mice. Reproductive Medicine and Biology
[3] Jiang et. al. 2022. Mitochondria: emerging therapeutic strategies for oocyte rescue. Reproductive Sciences
