Figure 1.

Schematic diagram showing the three anatomical regions of the oviduct (infundibulum, ampulla, and isthmus) and the regions of the oviduct where oocyte cumulus complexes and preimplantation embryos can be found. Oocyte cumulus complexes are ovulated from ovaries (#1), picked-up by the outer surface of the infundibulum (#2), and moved toward the ostium (unlabeled arrow) by ciliary beating then into the ampulla for fertilization (#3). Fertilized eggs and embryos are transported through the isthmus to the uterine cavity where they then can implant in the uterine wall.