The cryopreservation of human gamete has long been in development for decades. It has been proved that the goal of conception can be realized by the adoption of cryopreservation of sperm through artificial insemination ever since 1953. On the other hand, due to the larger size of the ovum and embryo which tends to be damaged by the formation of ice crystals during the freezing process, the case of successful thawed egg has never been reported until 1986. Compared with spermatozoa, the cryopreservation ovum technique is more difficult and with obviously lower efficiency. Thanks to the rapid development of vitrification, a type of refrigeration technology that applies the techniques of cell dehydration and hypervelocity cooling, we are able to effectively reduce the formation of ice crystals within the cells during the freezing process, which has greatly improved the survival probability of defrosted ovum and embryo in recent years. In 1999, the first live birth from frozen human egg is precisely a success breakthrough based on this technique, and the research in recent years has also proven that the survival rate of frozen ovum under vitrification is not different from fresh eggs. Therefore in 2012, the fact that the refrigeration technology of vitrification can be used in routine clinical practice or work is recognized by the American Society for Reproductive Medicine. The cryopreservation of frozen sperm, egg, and embryo has already become our regular routine and the refrigeration equipment for vitrification we employ is believed to be the best commercially available on for optimum efficiency. The suitable targets for egg cryopreservation include: egg donors, those planning delayed fertility, patients who are currently receiving treatment for test-tube baby yet fail to acquire the sperm, those who have to undergo therapeutic cure (for example, chemotherapy) owing to other diseases (cancer for instance).
Applicable subjects for frozen embryo include women who have residual embryo, ovarian hyper-stimulation syndrome, have symptoms that are not compatible with embryo transplantation or implantation, have temporarily suspended treatmentdue to contracting a disease, and women that are in need of therapeutic treatment owing to infertility caused by autoimmune diseases.
Applicable subjects for frozen spermatozoa include sperm donors, males who plan for delayed fertility or have to undergo therapeutic cure (for example, chemotherapy) because of other diseases (cancer for instance), and male depositors (sperm storage) that partake in the treatment plan of test-tube babies.