The Pacific Fertility Center (PFC) located in San Francisco, California, has developed an oocyte vitrification program. This method allows preservation of eggs, which signifies an important breakthough in fertility studies.


            The new alternative method for freezing embryos is called “vitrification”. This method differs to the traditional one used by the slow freezing technique, which cools the sperms and embryos very slowly to sub zero temperatures. The slow freezing, however, does not work efficiently on unfertilized human eggs, being the rate of success only two in 100.

The vitrification method works at faster cooling rates. It uses higher concentrations of cryoprotectants to achieve this, and cells are cooled in rates of several thousands degrees per minute. That way, good quality oocytes can be preserved, and be eventually used for fertilization.

The method was used with donations of five women in their twenties. All of their oocytes were vitrified and afterwards offered to patients waiting for embryo donations. Overall, the results were stunning: the PFC had 7 out of 10 embryos implant after transfers to 6 women.

This implantation rate of 70 % is similar to the one seen in cases where oocytes haven´t been frozen, which means that the method might mean an enormous advance regarding fertilization procedures.