Effect of fast thawing and slow thawing on sperm quality

Abstract:

Objective：To investigate the effect of fast thawing and slow thawing methods on the sperm quality. Methods：A total of 50 semen samples were screened out from the Reproductive Center of Fujian Provincial Maternal and Children’s Hospital，and each sample was aliquoted into two parts and then cryopreserved by the liquid nitrogen vapor method. The two parts of the same semen were divided into two groups based on the methods used for thawing，i.e.，fast thawing or slow thawing，and were observed for the difference in the thawing effect. The thawing effect included sperm kinetic parameters，morphological parameters，sperm DNA fragmentation index（DFI），sperm motility at 1 h，3 h，6 h，and 24 h after thawing when kept at room temperature，and kinetic parameters of sperms after a discontinuous density gradient centrifugation. Results：There were no significant differences between the two groups in the sperm kinetic parameters and percentage of sperms with normal morphology after thawing（P>0.01）. Compared with the slow thaw－ing group，the fasting thawing group had significantly reduced values of the following：sperm DFI，deformity rate of sperm head，body，and tail，teratozoospermia index（ＴＺＩ），and sperm deformity index（SDI）（P<0.01）. There were no significant differences between the two groups in the sperm kinetic parameters at 1 h and 3 h after thawing when kept at room temperature（P>0.01），but the fasting thawing group had significantly improved sperm kinetic parameters at 6 h and 24 h after thawing（P<0.01）. There were no significant differences between the two groups in the sperm density，total motile sperm count，forward sperm motility，and sperm recovery after a discontinuous density gradient centrifugation（P>0.01）. Conclusion：Fast thawing is better than slow thawing for semen cryopreserved by liquid nitrogen vapor due to less damage produced to sperms by the former.