In two weeks of experimentation, the team had accomplished what other cryobiologists (literally, ``frost biologists'') had sought for two decades. ``It was not due to any brilliance on our part,'' recollects Mazur, ``but because the principles of cryobiology were well-enough established that we though we knew what we were doing.''
The technique was soon adopted by the livestock industry as a way of sharing the genetic wealth of superior cattle: Embryos are now routinely frozen in the United States, then air-expressed to waiting cows in, say, eastern Europe. ``If you make the cow superovulate, you can get up to 25 embryos from a single ovulation.'' Mazur notes, multiplying a prize cow's reproductive potential by a factor of dozens or even hundreds.
Embryo freezing remained low-profile until the 1980s, when it made its way to human fertility clinics. The technique was made famous--or infamous--by two thorny legal cases: An Australian couple died and a Tennessee couple divorced, derailing the original plans for their embryos. Theoretically, says Mazur, the embryos in such cases could remain in limbo--biologically and ethically--for hundreds or even thousands of years.
Despite the dilemmas surrounding human embryo freezing, Mazur is bullish on cryobiology's future uses: preserving endangered animal species--for example, implanting horses with embryos from rare zebras--and keeping research mice or fruit flies on inexpensive ice, protected from, say, laboratory fires or study-skewing mutations called ``genetic drift.'' Eventually, the frosty technique could also be adapted to preserve transplant-bound human organs while their host is gradually introduced to its new tissues.
Two decades after making news with the cool technique, Mazur still has a warm spot in his heart for it.
Date posted 5/10/94 (cel)