Cryobiological principles of embryo freezing.

During a cryopreservation process a preimplantation embryo has to undergo multiple changes in volume caused by osmotic forces. When parameters such as cryoprotectant and water permeability coefficients and their temperature coefficients are known, equations can be solved to predict the volume response of an embryo during cryopreservation. This approach will allow the development or modification of cryopreservation procedures using relatively few embryos.