# Comparative Analysis of the Oviducts in Wanyue Black Pigs with Different Parities Based on RNA-Seq

## TL;DR

This study explores how the number of pregnancies affects the oviduct in Wanyue Black pigs, identifying genes linked to reproductive function and early embryo development.

## Contribution

The study provides a systematic transcriptomic analysis of parity effects on oviduct function in an indigenous pig breed.

## Key findings

- High-parity sows showed upregulated genes related to oocyte maturation and hormone synthesis.
- Low-parity sows exhibited elevated activity in genes controlling ciliary motility for gamete transport.
- Key regulatory genes HSD3B1 and DNAI1 were identified as central to parity-related differences.

## Abstract

The present study aimed to elucidate molecular mechanisms underlying parity-mediated effects on sow reproductive function. While reproductive performance is parity-dependent, the oviduct’s specific contribution to this variation—particularly in indigenous breeds such as the Wanyue Black pig—has not been systematically characterized. Comparative RNA sequencing of oviduct transcriptomes between high-parity (9 parities) and low-parity (1 parity) sows identified 4218 differentially expressed genes. High-parity sows demonstrated upregulation of genes implicated in oocyte maturation and steroid hormone synthesis, thereby fostering a microenvironment conducive to early embryonic development. Conversely, low-parity sows exhibited elevated activity in genes controlling ciliary motility to optimize gamete transport. Key regulatory factors included HSD3B1, which mediates hormone synthesis, and DNAI1, which governs ciliary function.

This study investigates the molecular mechanisms underlying parity’s impact on sow reproductive function by comparing the transcriptome profiles of high-parity (9 parities) and low-parity (1 parity) Wanyue Black pigs. Oviduct tissues were collected and subjected to RNA-seq analysis. Differentially expressed genes (DEGs) were identified using the DESeq2 algorithm. A total of 4218 DEGs were detected, with 2421 up-regulated and 1797 down-regulated genes. Functional enrichment analysis using GO and KEGG revealed that these DEGs were significantly associated with reproductive pathways, including cilium movement, oocyte maturation, and steroid hormone biosynthesis. Protein–protein interaction (PPI) network analysis highlighted key genes such as HSD3B1 and DNAI1, which play central roles in the parity differences. The expression patterns of selected candidate genes were further validated by real-time quantitative reverse transcription polymerase chain reaction (RT-qPCR), and the results were consistent with the RNA-seq data, confirming the reliability of our findings. This study provides valuable insights into the molecular regulation of parity in sows and offers a theoretical basis for optimizing reproductive management and breeding strategies in pig production.