Embryo Freezing is a physical process of converting aqueous solutions into the glassy state on cooling escaping freezing where intracellular ice formation is prevented by the introduction of some agents and very rapid cooling also called Vitrification.
- The embryos are stored in liquid nitrogen at a low temperature of -196degC. Here they are kept in state of suspended animation where every kind of metabolic activity stops. These embryos can be kept in such state for as long as required.
- There are two techniques of cryopreservation, Slow freeze and Vitrification. Vitrified embryos have an excellent i.e more than 90% Freeze- thaw survival rate because of addition of cryoprotectant prior to cooling which acts as antifreeze and also increases the viscosity thereby preventing the crystal formation.