The purpose of this present study is to assess if addition of the synthetic polymers in maturation medium can influence cryotolerance and subsequently embryonic development of mammalian oocytes. We examined the roles of two polymers, including polyvinyl alcohol (PVA) and polyvinylpyrrolidone (PVP), on in vitro maturation (IVM), embryonic developmental capacity, and cryotolerance of goat oocytes. The present study includes two parts. At first, goat cumulus-oocyte complexes (COCs) were matured in a medium supplemented with 10% fetal bovine serum (FBS), 3 mg/ml PVP, or 1 mg/ml PVA, respectively. Data of oocyte with first polar body, cleavage, and blastocyst following parthenogenetic activation (PA) were recorded. Secondly, after maturation in the above medium, oocytes were vitrified using the Cryotop technique and then the morphology, cleavage and blastocyst formation of vitrified oocytes have been checked. The results demonstrated that the adding of PVP or PVA in maturation medium can't affect IVM of goat oocytes in comparison with FBS, as concern cumulus cell expansion, first polar body formation, and embryonic development. Additionally, without plunging into liquid nitrogen, only exposure to the vitrification and warming solutions cannot also influence the quality of oocytes, in terms of morphology, cleavage, and blastocyst formation. However, after IVM with synthetic polymers and vitrification, the ratio of oocytes with standard morphology in PVP or PVA group was only 59.47% ± 3.56% or 54.86% ± 5.19%, respectively, and was significantly less than that in the FBS group (89.37% ± 4.52%, P < 0.05). Furthermore, the cleavage ratio of oocytes in PVP or PVA group was 37.41% ± 4.17% or 27.71% ± 3.91% and was considerably less than that in the FBS group (64.97% ± 4.69%, P < 0.05). In addition, the cleavage ratio in PVP group was statistically higher than that in PVA group (P < 0.05). In terms of blastocyst development, a significant difference was observed between the synthetic polymer group and the FBS group (24.96% ± 3.62%, P < 0.05). However, the blastocyst ratio in the PVA group (7.51% ± 1.68%) was statistically less than the PVP groups (13.20% ± 4.59%, P < 0.05) and the FBS group (P < 0.05). In conclusion, two potential serum replacements, either PVP or PVA, can support IVM and embryonic development of goat oocytes at the concentration used in this study. But IVM with synthetic polymers supplemented to maturation medium may reduce the cryotolerance of oocytes. Additionally, the supportive function of PVP on embryonic development of vitrified oocytes might be better than that of PVA.

中文翻译：

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成熟培养基中合成聚合物的存在影响玻璃化山羊卵母细胞孤雌生殖激活后的低温耐受性和发育能力

本研究的目的是评估在成熟培养基中添加合成聚合物是否会影响哺乳动物卵母细胞的低温耐受性和随后的胚胎发育。我们研究了两种聚合物，包括聚乙烯醇 (PVA) 和聚乙烯吡咯烷酮 (PVP)，对山羊卵母细胞的体外成熟 (IVM)、胚胎发育能力和低温耐受性的作用。本研究包括两部分。首先，山羊卵丘-卵母细胞复合物 (COC) 在分别添加 10% 胎牛血清 (FBS)、3 mg/ml PVP 或 1 mg/ml PVA 的培养基中成熟。记录孤雌生殖激活（PA）后具有第一极体、卵裂和囊胚的卵母细胞的数据。其次，在上述培养基中成熟后，使用Cryotop技术将卵母细胞玻璃化，然后进行形态学，已经检查了玻璃化卵母细胞的卵裂和囊胚形成。结果表明，与 FBS 相比，在成熟培养基中添加 PVP 或 PVA 不会影响山羊卵母细胞的 IVM，因为涉及卵丘细胞扩增、第一极体形成和胚胎发育。此外，在不浸入液氮的情况下，仅暴露于玻璃化和加温溶液也不会影响卵母细胞的质量，包括形态、卵裂和囊胚形成。然而，经过合成聚合物IVM和玻璃化冷冻后，PVP组和PVA组标准形态的卵母细胞比例分别仅为59.47%±3.56%或54.86%±5.19%，明显低于FBS组（89.37 % ± 4.52%，P < 0.05）。此外，PVP或PVA组的卵母细胞分裂率为37。41% ± 4.17% 或 27.71% ± 3.91%，远低于 FBS 组（64.97% ± 4.69%，P < 0.05）。此外，PVP 组的卵裂率明显高于 PVA 组（P < 0.05）。在囊胚发育方面，合成聚合物组与 FBS 组之间存在显着差异（24.96% ± 3.62%，P < 0.05）。然而，PVA组的囊胚率（7.51%±1.68%）在统计学上低于PVP组（13.20%±4.59%，P<0.05）和FBS组（P<0.05）。总之，两种潜在的血清替代品，PVP 或 PVA，可以在本研究中使用的浓度支持山羊卵母细胞的 IVM 和胚胎发育。但是在成熟培养基中添加合成聚合物的 IVM 可能会降低卵母细胞的耐低温性。此外，