The extracellular vesicles (EVs) of uterine flushing fluids (UFs) mediate intrauterine communication between conceptus and uterus in pigs. The small RNAs of UFs-EVs are widely recognized as important factors that influence embryonic implantation. However, small RNAs expression profiles of porcine UFs-EVs during peri-implantation are still unknown. In this study, cup-shaped EVs of porcine UFs on days 10 (D10), 13 (D13) and 18 (D18) of pregnancy were isolated and characterized. The expression of small RNAs in these EVs was comprehensively profiled through sequencing. A total of 152 known microRNAs (miRNAs), 43 novel miRNAs, 6248 known Piwi-interacting RNAs (piRNAs) and 110 novel piRNAs were identified. Among these small RNAs, RT-qRCR results indicated that ssc-let-7f-5p, ssc-let-7i-5p and ssc-let-7g were differentially expressed during the three stages. Bioinformatics analysis showed that the miRNAs differentially expressed in the three comparisons (D10 vs D13, D13 vs D18 and D10 vs D18) were involved in important processes and pathways related to immunization, endometrial receptivity and embryo development, which play important roles in embryonic implantation. Our results reveal that EVs from porcine UFs contain various small RNAs with potentially vital effects on implantation. This research also provides resources for studies of miRNAs and piRNAs in the cross-talk between embryo and endometrium.

子宫冲洗液（UFs）的细胞外囊泡（EVs）介导猪的子宫和子宫之间的子宫内通信。UFs-EV的小RNA被广泛认为是影响胚胎植入的重要因素。然而，在猪的UF-EVS的小RNA表达谱围-植入仍是未知的。在这项研究中，分离并鉴定了猪UFs在怀孕第10天（D10），第13天（D13）和第18天（D18）的杯状EV。通过测序全面剖析了这些电动汽车中小RNA的表达。总共鉴定出152个已知的microRNA（miRNA），43个新颖的miRNA，6248个已知的Piwi相互作用RNA（piRNA）和110个新颖的piRNA。在这些小RNA中，RT-qRCR结果表明，在三个阶段中，ssc-let-7f-5p，ssc-let-7i-5p和ssc-let-7g差异表达。生物信息学分析表明，在三个比较中（D10与D13，D13与D18和D10与D18）差异表达的miRNA参与了与免疫，子宫内膜容受性和胚胎发育相关的重要过程和途径，在胚胎植入中起着重要作用。我们的研究结果表明，猪超滤膜中的电动汽车含有多种小RNA，对植入具有潜在的重要影响。该研究还为研究胚胎与子宫内膜之间的对话中的miRNA和piRNA提供了资源。