Physiological and biochemical studies on freezability boar spermatozoa

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The effects of exposure to 2-hydroxyprophl-beta-cyclodextrin(HBCD) and methyl-beta-cyclodextrin(MBCD) on the freezability and cold shocked sensitivity of boar spermatozoa were investigated in the first experiment. The motility, progressive motility and velocity of either cold-shocked or frozen-thawed spermatozoa in cyclodextrin exposure treatments were significantly higher than those of the control. Preloading cyclodextrin with cholesterol-3 sulfate resulted in a decrease in all aforementioned criteria. These observations demonstrate that the artificial modification of its membrane improves the resistance of boar spermatozoa to cold shock and cryopreservation stress. We next examined whether the exposure of spermatozoa to seminal plasma before freezing decreases its freezability, assessed by %motile cells and in vitro penetration ability using IVF and chlortetracycline fluorescence assessment. When subjected to cryopreservation, the spermatozoa incubated in seminal plasma before freezi … More ng showed significantly lower levels of post-thaw motility than did spermatozoa incubated in modified Hulsenberg VIII diluents. The incubation of spermatozoa in seminal plasma also significantly prevented frozen-thawed spermatozoa from penetrating the oocytes. The next experiment, using unfrozen spermatozoa, was to determine if the incubation of spermatozoa with seminal plasma reduced the penetration ability before freezing, resulting in a significantly lower penetration rate after freezing compared with spermatozoa incubated without seminal plasma. The penetration competence of unfrozen spermatozoa was also found to be significantly decreased by incubation in seminal plasma, but to difference in motility was observed between the treatments with seminal plasma and modified Hulsenberg VIII diluents. It was concluded that ejaculated seminal plasma contains some factor(s) that modified the sperm before freezing, negatively influence the freezability and penetration competence of spermatozoa after freezing. Less