Immediately after the egg retrieval, the embryologist, an expert in the science of oocyte cryopreservation (the technical term for egg freezing), will rinse, incubate, and prep your eggs for freezing. Before the process of egg cryopreservation takes place, the embryologist will remove the cells that surround the egg, allowing her to see the egg clearly so she can evaluate the stage of maturation. Only mature, viable eggs are frozen, because these are the only ones that can become correctly fertilized later on. Typically, about 80% of eggs retrieved are deemed mature and suitable for freezing.
After determining which eggs are suitable for freezing, the embryologist will expose each egg to increasingly concentrated levels of cryoprotectants, substances that prevent the formation of ice crystals that can damage the egg. Then, each egg will be placed into a straw, about the diameter of a piece of spaghetti, which has been carefully labeled with your name and unique identification number. All the straws containing your eggs—and only your eggs—are immersed in liquid nitrogen and placed into one larger container, called a goblet, which is also labeled with your name and unique identification number. The goblet is placed inside a storage tank filled with liquid nitrogen, which keeps your eggs preserved indefinitely.
After identifying the mature eggs, the embryologist will expose each one to increasingly concentrated levels of cryoprotectants, substances that prevent the formation of ice crystals during the egg cryopreservation process. This is important, as ice crystals can damage the egg cell. Then, each egg will be placed into a straw, about the diameter of a piece of spaghetti, which has been carefully labeled with your name and unique identification number.
All the straws containing your eggs (and only your eggs) are immersed in liquid nitrogen, in which they freeze almost instantly. Then, they’re placed into one larger container called a goblet, which is also labeled with your name and unique identification number. The goblet is placed inside a storage tank filled with liquid nitrogen, which keeps your eggs preserved indefinitely.
Vitrification is a “flash freezing” technique that cools cells so quickly to a temperature of -196º Celsius (about -320º Fahrenheit) that they become “glass-like,” or “vitrified,” minimizing the chance that the water inside the cells will form damaging ice crystals. This is especially important for egg freezing, since eggs (as opposed to other things we might freeze, like sperm) are large size cells with a high content of water.
Vitrification is superior to any other method of egg cryopreservation. Studies have demonstrated that egg survival rates (meaning the percentage of eggs that are still viable after they’re thawed) increase from 61% after slow freezing—the older method of egg cryopreservation—to 91% after vitrification. However, not every practitioner offering egg freezing uses vitrification.
Here at Extend Fertility, vitrification is the cornerstone of our lab. In fact, we use the Cryotec method, an even more successful form of vitrification. The Cryotec method was developed by Dr. Masashige Kuwayama, long considered the foremost authority on egg vitrification. It consists of a specific set of strict protocols for egg cryopreservation (the procedure that the lab team uses to freeze the eggs). These protocols increase the egg survival rate to closer to 100%.
Our laboratory team has unique expertise in this cutting edge method. The assistant director of our embryology lab, Dr. Leslie Ramirez, studied with Dr. Kuwayama to perfect her technique. Extend Fertility is Dr. Kuwayama’s East Coast representative laboratory; before any other cryogenic lab is permitted to use this method, their embryologists must train with Dr. Ramirez.
Our lab has been specially designed to support effective egg cryopreservation in the cleanest, safest environment possible. We’ve installed a unique air handling system in the lab to remove potentially harmful particulates. We’ve implemented temperature controls on all lab surfaces to keep them at 37ºC (normal body temperature), to maintain egg quality. And our lab’s custom design, developed with Dr. Ramirez’s oversight, ensures optimal workflow for egg cryopreservation procedures.