Morris G J, Faszer K, Green J E, Draper D, Grout B W W, Fonseca F
Asymptote Ltd, St John's Innovation Centre, Cambridge, UK.
Theriogenology. 2007 Sep 15;68(5):804-12. doi: 10.1016/j.theriogenology.2007.06.009. Epub 2007 Jul 23.
The cellular damage that spermatozoa encounter at rapid rates of cooling has often been attributed to the formation of intracellular ice. However, no direct evidence of intracellular ice has been presented. An alternative mechanism has been proposed by Morris (2006) that cell damage is a result of an osmotic imbalance encountered during thawing. This paper examines whether intracellular ice forms during rapid cooling or if an alternative mechanism is present. Horse spermatozoa were cooled at a range of cooling rates from 0.3 to 3,000 degrees C/min in the presence of a cryoprotectant. The ultrastructure of the samples was examined by Cryo Scanning Electron Microscopy (CryoSEM) and freeze substitution, to determine whether intracellular ice formed and to examine alternative mechanisms of cell injury during rapid cooling. No intracellular ice formation was detected at any cooling rate. Differential scanning Calorimetry (DSC) was employed to examine the amount of ice formed at different rate of cooling. It is concluded that cell damage to horse spermatozoa, at cooling rates of up to 3,000 degrees C/min, is not caused by intracellular ice formation. Spermatozoa that have been cooled at high rates are subjected to an osmotic shock when they are thawed.
精子在快速冷却过程中所遭遇的细胞损伤常常被归因于细胞内冰晶的形成。然而，目前尚未有细胞内冰晶形成的直接证据。莫里斯（2006年）提出了另一种机制，即细胞损伤是解冻过程中渗透压失衡的结果。本文探讨了在快速冷却过程中是否会形成细胞内冰晶，或者是否存在其他机制。在冷冻保护剂存在的情况下，马精子以0.3至3000℃/分钟的一系列冷却速率进行冷却。通过低温扫描电子显微镜（CryoSEM）和冷冻置换来检查样本的超微结构，以确定是否形成细胞内冰晶，并研究快速冷却过程中细胞损伤的其他机制。在任何冷却速率下均未检测到细胞内冰晶的形成。采用差示扫描量热法（DSC）来检测不同冷却速率下形成的冰量。得出的结论是，在高达3000℃/分钟的冷却速率下，马精子的细胞损伤并非由细胞内冰晶的形成所致。快速冷却后的精子在解冻时会受到渗透压冲击。
