How are the donor eggs frozen?
An embryologist evaluates the eggs once they have been retrieved from the egg donor. Only mature eggs of top quality will be selected for cryopreservation – freezing and storing of the donor eggs.
The eggs are vitrified which means that the eggs are frozen rapidly to prevent possible ice crystal formation that could damage the eggs. Vitrification results in high survival numbers when the eggs are later warmed, and overall success rate with vitrified eggs approaches that of fresh donated eggs. After being vitrified, the eggs are stored in liquid nitrogen, until they are used for fertility treatment.
Read more about the egg donor screening proces here