173Cell and Materials Interface in Cryobiology and Cryoprotection
their ability to be fertilized. Since then, numerous research centers worldwide have
published reports on successful pregnancies after cryopreservation.
73–77
However,
the clinical efciency remained very low, that is, 2%–4%,
78
probably due to poor
survival, fertilization, and development of the cryopreserved oocytes.
79
Many reports
on animals showed that vitrication was used at both the germinal vesicle stage and
metaphase II stage.
80,81
Hunter etal.
82
attempted vitrication of human oocytes using mixed CPAs and
achieved survival rate of 65% and fertilization rate of 45%. EG has been frequently
used for the vitrication of oocytes because of its low toxicity and ability to p ...