Survival of cow blastocysts utilizing short freezing curves.

Blastocysts can survive direct transfer into liquid nitrogen after programmed freezing in 1.4 M glycerol to -29 degrees C when thawed by direct transfer into water at 37 degrees C. This observation facilitates the use of deep freezing of blastocysts in embryo transfer procedures. This makes the requirement for a special apparatus for the freezing procedure less demanding.