Improving cryopreservation systems.

Cryopreservation of oocytes and embryos is a crucial step for widespread practical application of other techniques in domestic animal embryology. However, in contrast to the rapid development of procedures in the eighties and early nineties of the last century, new advancements with profound practical consequences have only been recently achieved. As a result of a long and controversial development, an alternative group of methods, vitrification, has proved its efficiency and practicality in the past few years. The aim of this short review is to characterize strategies to prevent cryoinjuries, summarize the development of vitrification, overview its recent achievements, and provide a perspective about possible application. Authors strongly believe that the future of mammalian oocyte and embryo cryopreservation will be mainly based on vitrification, and the rate of advancement will be determined by the rate by which embryologists learn and acknowledge this new approach.