Qualité des gamètes et préservation de la fertilité

The main advantage of freezing oocytes is preserving the future fertility of women whose ovarian function is threatened by medical or surgical treatments and facilitating oocyte donation. The results of slow freezing of oocytes seem relatively dependent on the protocols used, most particularly on the sucrose concentration in the solutions of cryoprotective agents used. Today it seems that the use of low or medium-level concentrations of sucrose during the freezing process gives better results in terms of pregnancies and implantation than higher concentrations (0.3 mol/l), despite the sometimes less favorable results on oocyte survival after thawing. The cumulated pregnancy rates from frozen/thawed oocyte transfer are nearly equivalent to the results observed with frozen/thawed embryo transfer, which makes oocyte cryopreservation a valid alternative to embryo cryopreservation. Moreover, it seems that these results can be improved by the vitrification technique.