In Vitro Fertilization With Frozen Eggs
Unlike sperm and embryo cryopreservation, which have become routine processes in assisted reproductive technology, success with freezing eggs has historically been difficult to achieve. This is because the egg is the largest cell in the human body and contains a considerable amount of water.
When eggs are frozen, ice crystals form that can destroy the cell. To prevent this, the egg must be dehydrated prior to freezing. The water is then replaced by a special “antifreeze” that inhibits the formation of ice crystals. Because the eggshell hardens when frozen, sperm must be injected with a needle in order to fertilize the egg. This is known as ICSI (intracytoplasmic sperm injection) and is a standard technique also used in IVF.