Grade A eggs, fresh from the freezer
May 2nd, 2007 by Kishore
Oocyte cryopreservation. This is the fancy term for egg freezing. An oocyte is an immature ovum.
In the April 20th issue of Science, the increased usage of oocyte cryopreservation is discussed. Frozen oocytes is the future. Why? Unlike frozen embryos, there isn’t the ethical dilemna. It’s an unfertilized egg, no one considers that life yet. Frozen embryos have successfully been thawed and implanted via IVF. There have been about 300,000 frozen embryo births. However, frozen egg births are only account for about 300.
Back to the freeze. So why can’t we just freeze it and thaw it for later use? Sounds simple. Alton Brown will take it from here.
A new technique called ICSI (intracytoplasmic sperm injection) has been developed to essentially shoot a sperm right into the egg. This technique has revived the oocyte cryopreservation industry.
In the past, eggs have been frozen in a very slow, controlled method. The thaw is very fast. Commerical companies, such as Cryo Eggs, use this practice and claim 61% survival rate. The slow process yields smaller ice crystals which when thaw do less damage to the cell. The concern: long term studies have not been done on the resulting babies. The crystal formation may result in higher birth defects.
A new process has sprung up called vitrification. Essentially the egg is cooled incredibly fast, with liquid nitrogen, to prevent any ice crystal formation. Instead a glass-like clear cell is formed.
Even with all of these advances, a report in Fertility and Sterility by Oktay shows only 3 to 4% of frozen eggs yield a baby vs 6 to 8% with fresh eggs. Stick with fresh unless you absolutely need frozen.
Right now, cryopreservation is mainly used to help cancer patients with fertility. Within the next few years, there is hope that is will spread.
This entry was posted on Wednesday, May 2nd, 2007 at 1:53 pm and is filed under Fertility. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.