ABSTRACT
Cryopreservation, regardless of whether using a controlled rate of cooling or vitrification, requires the expulsion of intracellular water prior to cooling and replacing it with a permeable cryoprotectant. This indicates that a slower cooling rate, at least as associated with this amount of excess volume, was not the critical parameter it was previously thought to be, and that exposure to air when removing excess VS had a greater impact on survival. Seki and Mazur clearly showed with mouse oocytes that an extremely rapid warming rate not the cooling rate is the critical parameter. It is difficult to understand the rationale for this change in temperature, apart from the fact that the hydraulic permeability coefficient is temperature-dependent and, therefore, the rate of permeating cryoprotectant moving out of the oocyte at room temperature is slower.
