A touch of glass: cryopreservation of equine embryos by vitrification

The cryopreservation of equine embryos larger than 300 µm in diameter has proved problematic for many decades. However, there now exist protocols to undertake vitrification of such embryos with good pregnancy rates following their subsequent warming and transfer to recipient mares. This article discusses the reasons why equine embryos have proved so difficult to cryopreserve, and looks at cryopreservation methods before focusing on embryo vitrification. It also provides a historical perspective on the development of vitrification and details the latest techniques and emerging methodologies aimed at making embryo cryopreservation more accessible for practitioners.