Mammalian Oocyte Cryopreservation - Review.

Although oocyte cryopreservation represents one of the main objectives of the reproductive medicine and cryobiology in the last years, until now, regardless of the studied specie, there is no freezing protocol that will assure satisfactory survival rates after thawing. Oocyte cryopreservation is now one of the most problematic issues in cryobiology aria, especially because they are extremely sensitive to low temperatures, and the maintaining of a normal development potential after thawing is very difficult. For animals cryopreservation is offering the possibility of preserving the genetically valuable genotypes or endangered species, with reducing the costs associated with conventional breeding (shelter, food, bed, drugs, human resources, etc.). The main factors affecting the viability of the oocyte are cryoprotectors, freezing method, disruption of meiotic spindle, zona pellucida hardening and oocyte maturation stage. The present paper is aiming to review the historic of oocyte cryopreservation, the main factor involved in oocyte viability and current trends in gamete preservation. [ABSTRACT FROM AUTHOR]