Modern Trends: The Cryopreservation of Human Oocytes
Oocyte freezing has been considered as an experimental procedure for decade while it would be an important tool to use in IVF routine. In fact, a safe and efficient program would be of substantial benefit for infertile patients and also for women at risk of loosing their fertility due to radio or chemio therapy treatments. Moreover, egg cryopreservation could replace embryo freezing which instead involves important legal and ethical drawbacks. After the initial disappointment due to the low survival rate diverse methods have been developed raising the post thaw recovery. The fertilization and cleavage performance of frozen eggs is now similar to that of fresh sibling oocytes, even though not a great deal is known about the early implantation potential. There is an increased global interest in analyzing intrinsic factors connected to the ability of these embryos to give a live birth. What is clear, up to now is that certain oocyte cryopreservation protocols may affect cell division and thus being associated with low implantation rates. Other freezing methods, instead, seem not to affect the post implantation development and are going to be used in laboratories as an alternative mode to embryo freezing. It would be of immense importance that further randomized studies are carried out which may underline any possible differences between various technical approaches and also to further generate more analytical data on the cumulative pregnancy rates along with long term follow up of the babies born as associated with oocyte cryopreservation.