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, surgery, or antineoplastic treatments. Oocyte storage has faced technical difficulties compared with sperm or embryo cryopreservation because of the specific features of female germinal cell, as documented by the low number of births 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 some changes in the freezing protocol greatly improved the clinical efficiency with the birth of several healthy children.