Integrated multiple transcriptomes in oviductal tissue across the porcine estrous cycle reveal functional roles in oocyte maturation and transport.

Understanding the swine female reproductive system is important for solving issues related to reproductive failure and litter size. The oviduct is the site of fertilization. After fertilization, the fertilized egg moves to the uterus for implantation. Elucidating the regulatory mechanisms of the estrous cycle in the oviduct can improve our understanding of their roles. In this study, whole transcriptome RNA sequencing of oviduct tissue samples was performed throughout the estrous cycle to screen for differentially expressed genes (DEGs). The DEGs were classified into three clusters based on their expression patterns. Clusters 1 and 2 included genes involved in the physiological changes observed through the estrous cycle. The expression levels of Cluster 3 genes were downregulated specifically in the luteal phase; this was associated with calcium signalling and oocyte meiosis. In this study, we identified that the expression of genes in the oviduct influences oocyte transport and fertilization, which are the key functions of the oviduct. This study provides a basis for successful breeding in the pig industry and elucidating the mechanisms underlying the changes in the pig oviduct during the estrous cycle.