Survivability and developmental ability of embryos vitrified and warmed by different methods.

*<p>Current major protocol by vitrification with EFS20–EFS40 followed by rapid warming.</p>**<p>Storage at –80°C for 2 days. Embryos in other groups had been stored in LN2 before warming.</p>***<p>Significantly different (P<0.05 by Chi-squared test with Yates’ correction) from the corresponding rapid warming group. For compositions of the EFS types used, see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0049316#pone-0049316-t001" target="_blank">Table 1</a>.