Oocyte freezing: basics, current status and potential applications in reproductive biology

Over the past several decades, considerable effort has been expended toward the successful cryopreservation of various cells. While attempts at cryopreservation have been directed at different tissue types, one of the most vigorously pursued targets has been reproductive tissue. Historically, cryopreservation of sperm has existed for several decades. The earliest reports of pregnancies (Trounson et al., 1983) and births (Zeilmaker et al., 1984) from the cryopreservation of embryos occurred in the early 1980s. Presently, the freezing and storage of embryos following in vitro fertilization (IVF) is standard practice at most fertility clinics. In 2003, the CDC Assisted Reproductive Technology success rates report stated that 4,246 live births occurred out of 17,517 non-donor frozen embryo cycles. . Because the egg is a relatively voluminous cell with abundant cytoplasm, crystallization at the time of freezing may result in damage to the organelles. Secondly, a mature metaphase II oocyte contains a fragile spindle apparatus involved in cleavage. The purpose of this research study is to evaluate a method of freezing and thawing oocytes. This evaluation will be made by comparing the survival rates and rates of fertilization, cleavage and embryo quality of fresh oocytes and frozen-thawed oocytes which will be inseminated during the IVF (in vitro fertilization) treatment cycle. In addition, the same comparisons will be made between frozen oocytes from infertile women and those of egg donors. You are being asked to be in this study because you are currently undergoing in vitro fertilization