Cryopreservation of mammalian embryos: Derivation of a method

In 1972, a procedure was derived to cryopreserve mouse embryos. Over the past four decades, this procedure has been adapted to freeze embryos of more than twenty-five mammalian species. Cryopreservation of embryos has become a routine procedure in both veterinary and human medicine, having been used to freeze millions of embryos of mice and cattle, and many hundreds of thousands of human embryos. After transfer into appropriate foster mothers, cryopreserved embryos have developed into innumerable live offspring. This article describes the background that led to the derivation of the procedure and the events that transpired during its development. The first successful embryo cryopreservation procedure was developed by collaboration of three investigators, each bringing a special expertise and perspective to the project.