Oocyte freezing

Human oocyte cryopreservation is potentially an alternative solution to the ethical problems arising from embryo storage. In addition, oocyte freezing is the only method to preserve the reproductive capacity for women at risk of losing it because of premature ovarian failure, pelvic diseases, surger y, or antineoplastic treatments. Oocyte storage has faced technical difficu lties compared with sperm or embryo cryopreservation because of the specifi c features of female germinal cell, as documented by the low number of birt hs achieved after oocyte cryopreservation. Despite the early disappointing results regarding survival, fertilization, and cleavage rate, which led to only sporadic pregnancies in more than 10 years, the recent introduction of technical modification such as the intracytoplasmic sperm injection and so me changes in the freezing protocol greatly improved the clinical efficienc y with the birth of several healthy children.