Sowińska Natalia, Zahmel Jennifer, Niżański Wojciech, Hribal Romy, Fernandez-Gonzalez Lorena, Jewgenow Katarina
Department of Reproduction, Poznan University of Life Science, ul. Wołyńska 35, 60-637 Poznan, Poland.
Department of Reproduction Biology, Leibniz Institute for Zoo and Wildlife Research, Alfred-Kowalke-Straße 17, 10315 Berlin, Germany.
Animals (Basel). 2020 Aug 7;10(8):1371. doi: 10.3390/ani10081371.
Cryopreservation is important for animal fertility and biodiversity. Unfortunately, cryopreservation of feline oocytes is still an experimental technique. The aims of this study were to analyze the potential toxicity of the cryoprotectants in the vitrification solution (VS) on cat oocytes and to investigate whether the meiotic status of oocytes influences their developmental potential after vitrification. Two experiments were conducted with the VS composed of 20% ethylene glycol, 20% dimethyl sulfoxide, 20% fetal calf serum, 1.5 M trehalose, and 10% Ficoll PM-70: (1) toxicity assessment of the VS on immature cumulus oocyte complexes (COCs), and subsequently in vitro maturation (IVM) and in vitro fertilization; (2) assessment of the influence of the meiotic status on vitrification effectiveness, where immature and in vitro matured COCs were vitrified on the Cryotop. After rewarming, vitrified oocytes were subjected to IVM (immature) and intracytoplasmic sperm injection (ICSI) with fresh epididymal sperm. The toxicity test revealed no negative effect of oocyte exposure to the applied VS on their developmental potential ( > 0.05). Although the vitrification procedure itself significantly reduced the meiotic competence of oocytes, their meiotic status before vitrification (immature vs. in vitro matured) did not influence fertilization and morula rates. The only parameter affected by vitrification was the rate of oocytes suitable for ICSI, which was significantly lower for immature oocytes. Regardless of the meiotic status of vitrified oocytes, morphologically normal morulae were obtained. Moreover, the two meiotic stages examined are suitable for vitrification, with mature oocytes being a better choice when a well-equipped laboratory is available.
冷冻保存对于动物繁殖力和生物多样性至关重要。遗憾的是，猫卵母细胞的冷冻保存仍是一项实验技术。本研究的目的是分析玻璃化溶液（VS）中的冷冻保护剂对猫卵母细胞的潜在毒性，并研究卵母细胞的减数分裂状态是否会影响其玻璃化后的发育潜能。使用由20%乙二醇、20%二甲基亚砜、20%胎牛血清、1.5M海藻糖和10%聚蔗糖PM - 70组成的VS进行了两项实验：（1）VS对未成熟卵丘卵母细胞复合体（COCs）的毒性评估，随后进行体外成熟（IVM）和体外受精；（2）评估减数分裂状态对玻璃化效果的影响，将未成熟和体外成熟的COCs在Cryotop上进行玻璃化。复温后，对玻璃化的卵母细胞进行IVM（未成熟）和用新鲜附睾精子进行胞浆内精子注射（ICSI）。毒性试验表明，卵母细胞暴露于所用的VS对其发育潜能没有负面影响（>0.05）。尽管玻璃化程序本身显著降低了卵母细胞的减数分裂能力，但玻璃化前其减数分裂状态（未成熟与体外成熟）并不影响受精率和桑椹胚率。受玻璃化影响的唯一参数是适合ICSI的卵母细胞比例，未成熟卵母细胞的该比例显著较低。无论玻璃化卵母细胞的减数分裂状态如何，均可获得形态正常的桑椹胚。此外，所检测的两个减数分裂阶段均适合玻璃化，当有设备完善的实验室时，成熟卵母细胞是更好的选择。
