Fig. 2

Dynamic change in EV-mediated secretory activity of the glandular epithelium during early pregnancy. Upper panel: Schematic representation of the uterine glands. Uterine glands are located in the stromal compartment. Glands are composed of columnar epithelial cells covered with microvilli and cilia. The secretome is present in the glandular lumen and contain a population of EVs. MVBs are located at the apical site of glandular epithelial cells, releasing EVs into the lumen. Left panel: Cross section of a closed uterine gland on day 12 of pregnancy. A Glands had a small lumen diameter and were composed of cells covered with cilia and microvilli (higher magnification). B MVBs (black arrows) were located under the plasma membrane and contained a large number of vesicles (higher magnification). The lumen of the gland was filled with a heterogeneous in size population of EVs (yellow arrows) and numerous cilia and microvilli. Right panel: Cross section of a wide-open uterine gland on day 16 of pregnancy. C A large population of glandular cells with cilia and microvilli was observed. Glands were filled with a secretome containing a heterogeneous population of EVs (yellow arrows), cached between the microvilli. The apical site of the glandular epithelial cells showed MVBs (black arrow) filled with vesicles located under the plasma membrane (higher magnification). BV – blood vessel, C – cilia, DP – day of pregnancy, EVs – extracellular vesicles, GE – glandular epithelium, L – lumen, MV – microvilli, MVBs – multivesicular bodies, N – nucleus, SE – secretome, ST – stromal cells, TJ – tight junction, Vs – vesicles