Timelines: 1949

Livestock breeding breakthrough

Working at the British National Institute for Medical Research in London, Christopher Polge and Audrey Smith achieve a breakthrough in cell biology and animal science – they manage to inseminate cows artificially using frozen semen.

After a series of unsuccessful attempts to freeze cells for preservation, storage, and shipping, Polge and Smith experiment with glycerol and find that it prevents damage to cell membranes during freezing. The technique enables many livestock breeders to exercise greater control over the genetic composition of their herds. Within a decade, nearly every major cattle breeding center around the world has adopted cryopreservation methods.

After establishing the field of cryobiology in this way, Polge accepts a position at the Animal Research Station at Cambridge. In the late 1960s, he takes on an undergraduate intern from Nottingham named Ian Wilmut. Wilmut soon moves permanently to Cambridge to work on a Ph.D. in animal science. He continues to collaborate with Polge, and, in 1971, completes doctoral research on the low temperature preservation of boar semen.

With Ph.D. in hand, Wilmut moves to the Roslin Institute near Edinburgh in Scotland, where he eventually gains international fame for cloning Dolly the sheep using the nuclear transfer process. Dolly is the first mammal to be cloned from an adult somatic cell. Christopher Polge remains at the Animal Research Station until it closes in 1986. He then co-founds Animal Biotechnology Cambridge Ltd., and serves the firm as Scientific Director. The company aims to translate university research into commercial products.

After collaborating with Polge on the bull semen work, Audrey Smith stays on at the National Institute of Medical Research where she carries out cryobiological research with rodents. One of her experiments has a spectacular result – she finds that she can freeze hamsters for more than an hour and, under certain conditions, successfully revive them.