Ovarian cryopreservation and grafting: its potential for human reproductive biology and animal conservation

Ovarian cryobanking has considerable potential for fertility preservationand restoration and has been used to establish term pregnancies in mice, rats, sheep and humans, yet there is scope for progress towards in vitro and in vivo strategies to A) screen and improve outcomes of cryopreservationprocedures and to minimize ischemic damage following grafting, B) monitor folliculogenesis and hormonal feedback, C) screen for, and remove, malignant cells, D) generate antral folliclescontaining normal mature fertilizable oocytes even when orthotopic autografting is not possible, and E) combine ovarian cryopreservationwith more advanced reproductive technologies such as nuclear transfer(for animals only). In species such as mice a very diverse range of both cryopreservationand grafting strategies (including xenografting) has successfully generated live young. Human ovarian grafting is still a rare procedure and it is therefore encouraging that several babies have now been born. Progress has been slowest for species where compatible recipients are seldom available, such as with rare and endangered species. For these, further significant breakthroughs will be needed before cryobanked material can be reliably and efficiently used to generate new offspring.