techniques for ovarian tissue, whole ovary, oocyte and embryo cryopreservation

in recent years, preservation of fertility in women has been of great importance, especially in patients exposed to deleterious conditions on fertility. thus, cryopre-servation of human gametes, embryos and ovarian tissue has become an essential part of assisted reproduction. this approach limits the number of embryos transferred, while supernumerary oocytes and/ or embryos can be used in subsequent treatment cycles. furthermore, cryopreservation reduces the potential risk of hyperstimulation syndrome. cryopreservation is carried out by two techniques; the slow freezing method, and the more recent rapid procedure called vitrification technology. recently due the success and simplicity of vitrification, the balance between those two methods has been changed in advantage of vitrification. the use of slow freezing method has become controversial due to its difficulties, expense and respective low success rates in artificial reproduction. therefore, vitrification seems to win the battle and will be the cryopreservation method of the future.