title: S07_tissue
organism: Homo sapiens
description: Protocols: The detailed sample collection criteria are described in Apostolov et al., 2025. According to the provided summary, paired transcriptomic samples of endometrial tissue and uterine fluid extracellular vesicles (UF-EVs) were obtained from 19 fertile, healthy women. These samples were collected across four specific phases of the menstrual cycle: proliferative (n=4), early-secretory (n=5), mid-secretory (n=5), and late-secretory (n=5). Additionally, two unpaired UF-EV samples were collected from two healthy donors, one in the mid-secretory and one in the late-secretory phase.  The nucleic acid library construction protocol began with RNA extraction using QIAzol and miRNeasy micro kits, a process which consecutively separated the large and small RNA fractions. Quality and quantity of the extracted RNA were then assessed; a Bioanalyzer TapeStation 2100 was used for general quality checks, while the small RNA fraction was specifically quantified using a Qubit microRNA assay. For library construction, different kits were used depending on the target. Small RNA libraries were generated from 20 ng of starting material using a NEXTflex small RNA library preparation kit v4. In contrast, mRNA libraries were constructed using the TruSeq exome RNA library preparation kit (Illumina). This method enriches for coding regions via sequence-specific probes and does not depend on a poly(A) tail. The starting amount for uterine fluid extracellular vesicle (UF-EV) samples was 100 ng of RNA, or the maximum available quantity. Once the libraries were complete, they were pooled and evaluated with a High Sensitivity DNA ScreenTape D1000.