A total of eight oEVs samples (isolated from the Fallopian tubes of eight women) were used for total RNA extraction, using the exoRNeasy Maxi Kit (Qiagen, Hilden, Germany) according to the manufacturer’s protocol. The quality of the RNA samples was examined using a NanoDrop 2000 spectrophotometer (Thermo Scientific, Waltham, MA, USA) and standard denaturing agarose gel electrophoresis. Small RNA library preparation was performed using TruSeq Small RNA Sample Prep Kits (Illumina, San Diego, CA, USA). The quality-ensured RNA-seq libraries were then sequenced using Illumina Hiseq2000/2500. Identification of known miRNAs (mapped to the miRbase database) and read counting were processed using ACGT101-miR (LC Sciences, Houston, TX, USA). A modified normalization was used to correct copy number among different samples, as described previously (Li et al., 2016 ), and a miRNA was considered present when the normalized read count was >0 in all the samples. A heatmap was constructed using the normalized read counts of the known miRNAs in each oEV sample, using R (R version 4.0.3) with a heatmap via a custom written R script.