How do you like your eggs? Well if you want to push pause on your fertility, you might like yours frozen - flash frozen that is. Oocyte vitrification is the most recent technology that has made egg freezing a viable option for many women around the world.
Up until the fall of 2012, the only way to freeze eggs was the use of cryopreservation, a method that involves freezing tissue in liquid nitrogen at -148 degrees Fahrenheit. The one drawback to cryopreservation is the increased possibility of ice crystals forming, expanding the cells and potentially causing cell death. This lowered the rate of thawing and fertilization success, making it a rarely used option for oocyte freezing.
Vitrification on the other hand, flash freezes cells so there isn’t any time for ice crystals to form. The process involves the eggs being immersed in a combination of anti-freeze and sucrose (sugar), which will draw out any water. Next the oocyte is dipped in a higher concentration of anti-freeze, while being frozen instantaneously. This causes a state of suspended animation, making it possible to utilize the tissue at a later date without encountering the natural process of decay.
When it is time to thaw the frozen oocytes, they are removed from the anti-freeze solution and warmed. By avoiding any interference of ice in the cells, the success of ICSI or Intra-cytoplasmic sperm injection, where the embryologist injects a single sperm directly into the egg, is much higher than with cryopreservation. This has meant that 80-90% of eggs frozen using this process are viable, even years later.