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Effect of the cryopreservation method on sperm motility
Table I shows sperm quality parameters determined in fresh ejaculates and SUP sperm in the absence and presence of cryoprotectant before cryopreservation. These data show a slight (12%) reduction in the motility of SUP spermatozoa after 10 min of incubation with TEYG (P > 0.05), indicating a detrimental effect of the cryoprotectant. However, this effect could not be correlated with a change in DNA integrity (Figure 2, P > 0.05).
Figure
1 indicates that slow freezing with no cryoprotectant gives rise to a 29.1-fold decrease in sperm motility compared with slow freezing with a cryoprotectant (
P In contrast, sperm motility was 2.87 times lower when vitrification was conducted in the presence of cryoprotectant compared with vitrification with no cryoprotectant (Figure
1,
P The highest motility rates after vitrification were achieved using SUP spermatozoa on copper loops with no cryoprotectant (51.5 ± 4.5%), though these rates were similar to those shown by sperm slowly frozen using the cryoprotectant (46.7 ± 4.1%;
P > 0.5).
Effect of cryopreservation method on sperm DNA integrity
We observed no significant differences in the DNA integrity of prepared spermatozoa related to the freezing method or presence of a cryoprotectant (Figure 2; P > 0.5). The proportions of sperm showing undamaged DNA were 85.09 and 89.51%, respectively, for fresh sperm treated or not treated with the cryoprotectant, 84.62 and 83.53%, respectively, for the slowly frozen sperm with or without cryoprotectant, and 87.24 and 84.66%, respectively, for the vitrified sperm with or without cryoprotectant.
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