A myriad of locally produced factors into the microenvironment of the reproductive tract is regulated, not one-way but rather, through embryonic-maternal cross-talk. In this mini-review, the authors focused on the exosomes, which are cell-derived vesicles of 30-100 nm in diameter, as a communicating language facilitating this dialog. These nanovesicles are secreted from pre-implantation embryos, oviduct epithelium, and endometrium as well as from the placenta, and contain proteins, messenger RNA (mRNA), microRNA, and DNA cargoes, and have pleiotropic effects on both embryonic and maternal environments. A better understanding of the molecular mechanisms mediating this cross-talk will lead to the development of new regulating agents, with novel diagnostic, biological, and therapeutic potential for either supporting or hindering the normal reproductive functions.
Embryo-derived exosomes as seen by transmission electron microscope. TEM images show the presence of particles, ranging from less than 100 nm (A) to 30 nm (B), in an embryo-conditioned medium pellet isolated by differential centrifugation, after negative staining with uranyl acetate (more detailed methods for exosomes isolation are described in our previous report). A sketch showing the paracrine intercellular communication between embryos and endometrium, through the exosomes (C).