Oocyte cryopreservation and ovarian tissue banking

Oocyte cryopreservation, despite its impact on conservation of genetic reso urces, is not yet an established technology. Several problems need to be so lved before this technology can be applied regularly. Chilling membrane sus ceptibility and formation of ice due to the large volume of the cell are th e major problems observed. However, during the last years, several studies were done to obtain viable oocytes after cryopreservation. The addition of molecules known to stabilize membranes and the creation of freezing systems with rapid cooling throughout the transition phase have yielded a good per centage of viable immature and mature oocytes. More recently, storage of fe male gametes was achieved by cryopreservation of cortical ovarian tissue. T he possibility of restoring fertility by transplantation of frozen ovarian tissue or its long-term culture in vitro represents an important future mea ns of preserving the fertility of patients and of storing the gametes of ra re animals. (C) 2001 by Elsevier Science Inc.