ABSTRACT
As of March 2006, a total of 51 pregnancies (28 live births, 23 ongoing, and 40 children born) after vitrification of a human mature oocyte had been reported worldwide.1 We reported the first delivery in Japan following cryopreservation of a human mature oocyte in 2001.2 This was achieved by using the slow freezing method (SFM) with 1,2-propanediol (PROH) and mature oocytes. We also reported the first successful pregnancy and delivery after transfer of a single blastocyst derived from a vitrified human oocyte in 2005.3
Intracellular osmotic pressure at −30°C in the SFM is about 13 000 mOsmol/L, compared with 8000 mOsmol/L for the vitrification method (VM). Intracellular condition during cooling and warming is thus better with the VM than with the SFM.
