The cryobiology of assisted reproduction

Cryopreservation of human gametes and embryos has become an integral part of assisted reproduction. The major developments in cryopreservation technology have mirrored the rapid expansion of reproductive technology over the past 2 decades. It is now possible to cryopreserve sperm, oocytes and embryos at their various stages of development. The introduction of vitrification and rapid freezing techniques is gaining widespread recognition and may become the method of choice over traditional slow freezing methods. Ovarian tissue cryopreservation offers the hope of fertility preservation for women who are faced with potentially sterilizing medical or surgical treatments. Paralleling the introduction of cryobiology to assisted reproduction has been the realization of a number of moral and ethical issues related to gamete and/or embryo storage.