This prospective study aimed to determine the effects of dry nitrogen cryostorage on human sperm characteristics in comparison with liquid nitrogen cryostorage. For this purpose, 42 men undergoing routine semen analysis (21 normozoospermia and 21 with altered semen parameters) were analyzed. After slow freezing, half of the straws of each sample were randomly stored in liquid and dry tanks, at the top and bottom levels of the latter. After 6 months storage, thawed samples were treated by density gradient centrifugation and sperm characteristics were compared. There was no difference in sperm progressive motility (15.1% ± 14.2% vs. 15.1% ± 12.7%; p = 0.76), sperm vitality (25.5% ± 17.7% vs. 26.2% ± 19%; p = 0.71), percentages of acrosome-reacted spermatozoa (38% ± 8.5% vs. 38.5% ± 7.4%; p = 0.53) and DNA fragmentation spermatozoa (27.3% ± 12.4% vs. 28.5% ± 12.9%, p = 0.47) after cryostorage in the dry or the liquid nitrogen tank. Moreover, we did not observe differences between either cryostorage system for normal and altered sperm samples. This lack of difference was also observed whatever the floor level of cryostorage in the dry tank. The temperature measurement of the dry tank showed a stable temperature at -194 °C throughout storage whatever the storage floor level, guaranteeing the stability of the low temperatures suitable for human sperm storage. Because of its greater safety, dry storage without contact with the liquid phase should be preferred and can be a useful alternative for the cryostorage of human sperm samples.

中文翻译：

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干槽精子冷冻：一种准确的替代方法

这项前瞻性研究旨在确定与液氮冷冻相比，干氮冷冻对人类精子特征的影响。为此，对 42 名接受常规精液分析的男性（21 名正常精子症和 21 名精液参数改变）进行了分析。缓慢冷冻后，每个样品的一半吸管随机存放在液体和干燥罐中，分别位于后者的顶部和底部。储存 6 个月后，解冻的样品通过密度梯度离心处理并比较精子特征。精子进行性运动（15.1% ± 14.2% 对 15.1% ± 12.7%；p = 0.76）、精子活力（25.5% ± 17.7% 对 26.2% ± 19%；p = 0.71）、顶体反应精子（38% ± 8.5% vs. 38.5% ± 7.4%；p = 0.53）和 DNA 碎片精子（27.3% ± 12.4% vs. 28.5% ± 12.9%, p = 0.47) 在干燥或液氮罐中冷冻后。此外，我们没有观察到正常和改变精子样本的冷冻系统之间的差异。无论干燥罐中冷冻库的地板水平如何，都可以观察到这种差异的缺乏。干槽的温度测量显示，无论存储楼层如何，整个存储过程中温度都稳定在-194°C，保证了适合人类精子存储的低温稳定性。由于其更高的安全性，不与液相接触的干燥储存应该是首选，并且可以成为人类精子样本冷冻储存的有用替代方案。对于正常和改变的精子样本，我们没有观察到两种冷冻系统之间的差异。无论干燥罐中冷冻库的地板水平如何，都可以观察到这种差异的缺乏。干槽的温度测量显示，无论存储楼层如何，整个存储过程中温度都稳定在-194°C，保证了适合人类精子存储的低温稳定性。由于其更高的安全性，不与液相接触的干燥储存应该是首选，并且可以成为人类精子样本冷冻储存的有用替代方案。对于正常和改变的精子样本，我们没有观察到两种冷冻系统之间的差异。无论干燥罐中冷冻库的地板水平如何，都可以观察到这种差异的缺乏。干槽的温度测量显示，无论存储楼层如何，整个存储过程中温度都稳定在-194°C，保证了适合人类精子存储的低温稳定性。由于其更高的安全性，不与液相接触的干燥储存应该是首选，并且可以成为人类精子样本冷冻储存的有用替代方案。干槽的温度测量显示，无论存储层高低，整个存储过程中温度稳定在-194°C，保证了适合人类精子存储的低温稳定性。由于其更高的安全性，不与液相接触的干燥储存应该是首选，并且可以成为人类精子样本冷冻储存的有用替代方案。干槽的温度测量显示，无论存储楼层如何，整个存储过程中温度都稳定在-194°C，保证了适合人类精子存储的低温稳定性。由于其更高的安全性，不与液相接触的干燥储存应该是首选，并且可以成为人类精子样本冷冻储存的有用替代方案。