Department of Reproduction and Development, Reproductive Biomedicine Center, Royan Institute for Animal Biotechnology, ACECR, Isfahan, Iran.
Mol Reprod Dev. 2012 Jul;79(7):434-44. doi: 10.1002/mrd.22047. Epub 2012 May 22.
Oocyte vitrification and assisted oocyte activation have increasingly important roles in assisted reproductive technology. Yet, an important area of concern with matured oocyte cryobiology is that elements of oocytes intimately involved in metaphase-II arrest may be modified by cryopreservation. By comparing different cellular characteristics of unvitrified, vitrified-warmed, and unvitrified-activated oocytes, the present study investigated how vitrification-warming process may affect developmental competence of in vitro-matured sheep oocytes following parthenogenetic activation. Structural, ultrastructural, and molecular analyses indicated that the characteristics of vitrified-warmed oocytes vastly differed from fresh oocytes, instead resembling unvitrified-activated oocytes. For unvitrified oocytes, the highest blastocyst yield (41.8 ± 0.6%) was achieved using the maximum ionomycin concentration (5 µM), and importantly, the duration of ionomycin treatment was not of utmost importance at this concentration. In contrast, the maximum blastocyst yield of vitrified-warmed oocytes (28.4 ± 1.4%) was achieved with a minimal duration of ionomycin treatment (1 min), and further extending the duration dramatically reduced developmental potential of vitrified-warmed oocytes. These results suggested that vitrified-warmed oocytes may need an activation protocol different from unvitrified oocytes. In this respect, unvitrified oocytes were more sensitive to the concentration rather than the duration of ionomycin treatment when compared with vitrified oocytes, which were sensitive to the treatment duration. These results may provide a platform to improve the potential applications of vitrified oocytes in medicine and agriculture.
卵母细胞玻璃化和辅助卵母细胞激活在辅助生殖技术中具有越来越重要的作用。然而，成熟卵母细胞冷冻生物学的一个重要关注领域是，与中期 II 阻滞密切相关的卵母细胞的某些元素可能会因冷冻保存而发生改变。本研究通过比较未玻璃化、玻璃化-解冻和未玻璃化-激活的卵母细胞的不同细胞特征，研究了玻璃化-解冻过程如何影响体外成熟绵羊卵母细胞经孤雌激活后的发育能力。结构、超微结构和分子分析表明，玻璃化-解冻卵母细胞的特征与新鲜卵母细胞有很大差异，反而与未玻璃化-激活的卵母细胞相似。对于未玻璃化的卵母细胞，使用最大浓度的离子霉素（5 μM）可获得最高的囊胚率（41.8±0.6%），重要的是，在该浓度下，离子霉素处理的时间并不至关重要。相比之下，玻璃化-解冻卵母细胞的最高囊胚率（28.4±1.4%）是通过最短的离子霉素处理时间（1 分钟）获得的，进一步延长处理时间会显著降低玻璃化-解冻卵母细胞的发育潜能。这些结果表明，玻璃化-解冻的卵母细胞可能需要不同于未玻璃化卵母细胞的激活方案。在这方面，与玻璃化卵母细胞相比，未玻璃化卵母细胞对离子霉素处理的浓度更敏感，而不是时间，而玻璃化卵母细胞对处理时间更敏感。这些结果可能为提高玻璃化卵母细胞在医学和农业中的潜在应用提供了一个平台。
