Recent Advances and Emerging Applications in Embryo Vitrification for Livestock.

Abstract

Vitrification has progressively supplanted conventional slow freezing as the method of choice for embryo cryopreservation in both human medicine and animal production, particularly for in vitro-produced embryos and for species or developmental stages highly sensitive to conventional freezing. By combining very high cooling and warming rates with concentrated cryoprotectant solutions and minimal sample volumes, it largely prevents intracellular ice formation and, in experienced hands, consistently yields post-warming survival and developmental rates that exceed those obtained with traditional controlled-rate freezing. In this review, we synthesize recent technical and biological advances in embryo vitrification, with particular attention to cryoprotectant formulations, carrier devices, cooling-rate control and current strategies to enhance cryotolerance. For the main livestock species-cattle, horses, pigs and small ruminants-we outline the present state of this technology, highlighting where vitrification has become routine practice and where adoption remains limited or experimental. Despite the clear progress achieved, implementation in field conditions is still heterogeneous, and truly standardized, species-adapted protocols-ideally amenable to automation and direct transfer-are yet to be fully established.