How are eggs frozen?
After ovarian stimulation using medication, the eggs are retrieved from the patient using a needle. They are immersed for 40 seconds in a cryoprotective solution, then transferred to a liquid nitrogen bath, where they will be stored in reservoirs under highly strict surveillance. Studies tend to show that eggs frozen this way can be stored almost indefinitely.
Although it’s not a guarantee of success, vitrification of eggs in liquid nitrogen is a major technological breakthrough that freezes and unfreezes them with a relatively high survival rate. The eggs are rehydrated and warmed up in a liquid at 37°C before fertilizing them in vitro.