The miR-888 cluster family is composed of six miRNAs (i.e., miR-888, miR-890, miR-891a, miR-891b, miR-892a, miR-892b) that are exclusively expressed in the epididymis of humans and nonhuman primates. (a) Picture of a human epididymis showing the caput, corpus and cauda regions of the organ. (b) A study performed on six human epididymides indicates that the miR-888 cluster, including miR-892b, is highly expressed in the corpus and cauda regions of the human epididymis, but is almost undetectable in the proximal region. Adapted from Belleannée.96 (c) The miR-888 cluster consists of extracellular miRNAs found in extracellular vesicles from seminal plasma of normozoospermic controls (n) and vasovasostomized (VV) donors, but is absent from seminal plasma of vasectomized donors (v), which is devoid of epididymal secretions. (d) Venn diagram representing the number of mRNA targets of the miR-888 cluster from in silico studies. Each miRNA targets different mRNAs that are involved in immune response regulation as shown in (e) ingenuity analysis for miR-890.