Department of Anatomy, Histology, Forensic Medicine and Orthopaedics, La Sapienza University, Rome, Italy.
Eur J Histochem. 2012 Aug 10;56(3):e38. doi: 10.4081/ejh.2012.e38.
Since the introduction of human assisted reproduction, oocyte cryopreservation has been regarded as an attractive option to capitalize the reproductive potential of surplus oocytes and preserve female fertility. However, for two decades the endeavor to store oocytes has been limited by the not yet optimized methodologies, with the consequence of poor clinical outcome or of uncertain reproducibility. Vitrification has been developed as the promising technology of cryopreservation even if slow freezing remains a suitable choice. Nevertheless, the insufficiency of clinical and correlated multidisciplinary data is still stirring controversy on the impact of this technique on oocyte integrity. Morphological studies may actually provide a great insight in this debate. Phase contrast microscopy and other light microscopy techniques, including cytochemistry, provided substantial morphofunctional data on cryopreserved oocyte, but are unable to unraveling fine structural changes. The ultrastructural damage is one of the most adverse events associated with cryopreservation, as an effect of cryo-protectant toxicity, ice crystal formation and osmotic stress. Surprisingly, transmission electron microscopy has attracted only limited attention in the field of cryopreservation. In this review, the subcellular structure of human mature oocytes following vitrification is discussed at the light of most relevant ultrastructural studies.
自人类辅助生殖技术问世以来，卵母细胞冷冻保存被认为是一种有吸引力的选择，可以利用多余卵母细胞的生殖潜能并保存女性的生育能力。然而，在过去的二十年中，卵母细胞的储存一直受到尚未优化的方法学的限制，其结果是临床结局不佳或可重复性不确定。玻璃化已被开发为冷冻保存的有前途的技术，尽管慢速冷冻仍然是一种合适的选择。然而，临床和相关多学科数据的不足仍然引发了关于该技术对卵母细胞完整性影响的争议。形态学研究实际上可以为这场辩论提供重要的见解。相差显微镜和其他包括细胞化学在内的光学显微镜技术为冷冻保存的卵母细胞提供了大量的形态和功能数据，但无法揭示精细的结构变化。超微结构损伤是与冷冻保存相关的最不利事件之一，其原因是冷冻保护剂毒性、冰晶形成和渗透压力。令人惊讶的是，透射电子显微镜在冷冻保存领域仅引起了有限的关注。在这篇综述中，根据最相关的超微结构研究，讨论了人类成熟卵母细胞在玻璃化后的亚细胞结构。
