Developments in reproductive technology are occurring at a rapid rate in agricultural animal science as well as in human biology. In vitro fertilization, embryo culture, preservation of embryos by freezing (cryopreservation) and cloning technology yield embryos that are produced outside of the female reproductive system. Embryo transfer permits continued survival of embryos by insertion into the female reproductive system.

Obviously, there would be no need for embryo transfer if mammalian embryos could be cultured to maturity in the laboratory. While cell culture in vitro has made remarkable strides, embryos can be sustained in culture for only a few days. Thus, their survival is dependent upon transfer to the hospitable and nurturing environment of the uterus of a foster mother. While embryo transfer may seem to be high technology, it actually got its start well over a century ago. The uterus of one variety of rabbit (a...