SC exosomes interact with female epithelial cells. (A) Schematic of female reproductive tract shown in B. mp, posterior mating plug (autofluorescent); ut, uterus; sr, seminal receptacle; spt, spermathecae; ovi, oviduct. (B–D) actin>CD8-RFP–expressing (B and C) or wild-type (D) females mated to SC>CD63-GFP males. (B) CD63-GFP exosomes are found in the uterus (green arrow) and oviduct (green asterisk). (C and D) These exosomes accumulate at the apical surface of female reproductive tract epithelial cells (arrows), which are either marked with CD8-RFP (C; Video 4) or unmarked (D). DAPI stains nuclei. In D, the reproductive tract is stained with an antibody against human CD63 to confirm that GFP and CD63 colocalize. Specific spermathecal cells exhibit weak autofluorescence. Bars: (B) 200 µm; (C) 20 µm; (D) 5 µm.