Embryo Transfer Review Mrs. Tarver What is a major factor in embryo transfer success? • Successful control of estrus in donor and recipient females Why is embryo transfer done surgically in pigs and sheep? • It is difficult to pass an embryo collection device through the cervix of the ewe or sow. What is the transferred survival rate of an embryo? • 55% to 70% What is an acceptable difference in estrus between donor and recipient? • Only up to one day difference in estrus cycles is acceptable between donor and recipient females. What is the optimal placement for implantation? • The embryo is expelled into the uterine horn that is on the same side as the ovulated ovary to optimize the embryo implantation rate. When and where was the first embryo transfer performed? • Using rabbits, a researcher at the University of Cambridge in 1890 performed the first embryo transfer. What is superovulation? • The release of many eggs (oocytes) during a single estrus period Embryos in early stages of development should be deposited where? • Oviduct What is the most accurate predictor of embryo transfer success rate? • The stage of embryonic development After superovulation when should the female be bred? • 12-24 hours after she comes into heat What is in vitro fertilization? • Laboratory technique for conception of an embryo outside the mother’s body What is a Foley catheter? • A specially designed catheter used when collecting embryos using non-surgical methods. How do conception rates compare for surgically vs. non-surgically transferred embryos? • Conception rates are up to 5% greater with surgical transfer Why is synchronization of estrus important for embryo transfer? • It is important to establish a uniform uterine environment for the embryo Discuss embryo evaluation and the grading scale. • After collection, the embryos are evaluated for quality using a stereoscopic microscope. Shape, color, texture, and size are some factors considered during the evaluation. Embryos are graded on a scale from one (excellent) to four (poor).