Transcriptomes of human oocytes during in vitro maturation

We aimed to reveal gene expression profiles of human oocytes at each maturation stage by single cell RNA-seq analyses. We investigated transcriptomes of immature oocytes at the germinal vesicle (GV) stage, maturating oocytes at the metaphase I (MI) stage and in vitro matured oocytes at the metaphase II (MII) stage. In this study, transcriptomes for oocytes at different maturation stages were examined using single cell RNA-seq. Surplus oocytes, which are normally discarded as medical waste, were subjected to this study. Immature oocytes at the time of oocyte collection were used for in vitro maturation, and oocytes that reached the MII stage until 5.5-7 hours after the oocyte collection were used for infertility treatment. The remaining oocytes were regarded as surplus oocytes. Those were again subjected to incubation for in vitro maturation and their morphology was assessed during 7.5-9 hours after the oocyte collection. At this stage, oocytes at the GV, MI, and MII stages were collected and subjected to RNA-seq. Moreover, some remaining oocytes were further cultured for 15-16.5 hours and oocytes that reached each maturation stage at 24 hours after the oocyte collection were also used for RNA-seq analyses.