Department of Veterinary Gynaecology and Obstetrics, College of Veterinary Science, DUVASU Mathura, UP, India.
Department of Veterinary Physiology, College of Veterinary Science, DUVASU Mathura, UP, India.
Cryo Letters. 2024 Jul-Aug;45(4):212-220.
Cryopreservation of spermatozoa involves reduction of temperature to a subzero level, leading to increased longevity. However, temperature reduction has a significant effect on sperm membranes.
To evaluate the impact of the rate of temperature drop during the first phase of freezing on subtle membrane changes in cryopreserved bull spermatozoa.
Thirty-two ejaculates from four bulls (eight ejaculates/bull) were collected using artificial vagina while keeping a 3 to 4 days gap between two collections. Diluted semen samples were equilibrated at 5 degree C for 4 hours. The samples were then placed in a pre-programmed semen freezer. The first phase of freezing, that is, 5 degree C till -10 degree C was subjected to three different temperature drop rates: accelerated (F), moderate (F), and slow (F), at 20 degree C per min, 10 degree C per min and 5 degree C per min, respectively. After thawing, spermatozoa were assessed for percentage live, plasma, and acrosomal membrane integrity, along with the external appearance of phosphatidyl serine, indicating apoptosis.
A significant difference (p < 0.05) in viability, plasma membrane integrity (HOS test), and acrosome membrane integrity (PSA test) was observed between F and the other groups. However, the parameters did not significantly differ between F and F. The annexin V-PI assay (AN/PI) categorized four types of sperm populations: non-apoptotic and viable (AN-/PI-), apoptotic and viable (AN+/PI-), non-apoptotic and non-viable (AN-/PI+), and apoptotic and non-viable (AN+/PI+). The proportion of spermatozoa with (AN-/PI-) and (AN+/PI+) differed significantly (p < 0.05) between F and the other groups. The values for apoptotic and viable (AN+/PI-) and non-apoptotic and non-viable (AN-/PI+) sperm were not significantly different among all freezing categories.
A slower temperature drop rate (freezing rate) during the first phase of freezing results in less damaging, subtle membrane changes. Doi.org/10.54680/fr24410110312.
精子的冷冻保存涉及将温度降低到亚低温水平，从而延长精子的寿命。然而，温度降低对精子膜有显著影响。
评估冷冻保存牛精子在第一阶段降温速率对细微膜变化的影响。
使用人工阴道收集 4 头公牛的 32 个精液样本（每公牛 8 个样本），两次采集之间间隔 3-4 天。稀释精液样本在 5°C 下平衡 4 小时。然后将样本放入预编程的精子冷冻机中。第一阶段的冷冻，即从 5°C 到-10°C，分为三种不同的降温速率：快速（F）、中速（F）和慢速（F），降温速率分别为每分钟 20°C、每分钟 10°C和每分钟 5°C。解冻后，评估精子的活率、血浆和顶体膜完整性，以及外显磷脂酰丝氨酸，表明细胞凋亡。
F 组与其他组之间的活力、质膜完整性（HOS 试验）和顶体膜完整性（PSA 试验）存在显著差异（p<0.05）。然而，F 组和 F 组之间的参数没有显著差异。膜联蛋白 V-PI 测定法（AN/PI）将四种精子群体分类：非凋亡和存活（AN-/PI-）、凋亡和存活（AN+/PI-）、非凋亡和非存活（AN-/PI+）和凋亡和非存活（AN+/PI+）。F 组与其他组之间的精子（AN-/PI-）和（AN+/PI+）比例有显著差异（p<0.05）。所有冷冻分类中，凋亡和存活（AN+/PI-）和非凋亡和非存活（AN-/PI+）精子的比例没有显著差异。
第一阶段冷冻过程中较慢的降温速率（冷冻速率）会导致较少的、细微的膜变化。doi.org/10.54680/fr24410110312.
