In 1972 preimplantation mammalian embryos were successfully cryopreserved.

The method was very time consuming. Slow cooling (1 degree/min or less) to about -80 degrees Centigrade. The embryos were then placed in liquid nitrogen. Also, the embryos needed to be thawed slowly and cryoprotent added and removed in many small steps. This was a lot of work.

The first reported human pregnancy from frozen embryos was reported in 1983 by Trounson and Mohr.

Most of the research has been done on mouse embryos. Development of frozen thawed mouse embryos, in vitro and in vivo, is not statistically reduced as compared to their non-frozen controls. This is not yet true for any other species.



Information excerpted from Advanced Fertility Center Chicago, IL