The oocytes from small antral follicle have low developmental potential to reach blastocyst due to incomplete cytoplasmic maturation during in vitro maturation (IVM). Thus, we developed an in vitro culture system for porcine oocytes derived from small antral follicles with l-ascorbic acid supplement during pre-maturation (pre-IVM) to support their development to blastocyst stage. Besides that, how l-ascorbic acid effect on the developmental competence of porcine oocytes with a special focus on histone modifications will be elucidated. The in vitro culture process consisted of two steps. The first step is 22 h of pre-IVM and the second step is 42 h of IVM. We utilized dibutyryl-cyclicAMP (dbcAMP) with L-ascorbic supplement during pre-IVM. Based on the result of this procedure, we proposed that the best culture condition in which hormone human chorionic gonadotropin (hCG) be added during the last 7 h of pre-IVM and continued culture to complete IVM. We observed that, in this culture system, the meiotic competence of porcine oocytes derived from small follicles was as high as those derived from large follicles after undergoing IVM. In addition, our study suggested that l-ascorbic acid supplementation at 100 μg/mL sharply enhanced the developmental potential of porcine oocytes. Interestingly, oocytes from small antral follicles treated with l-ascorbic acid could obtain the blastocyst quantity and quality as high as that of large antral follicles. The treated groups showed a significantly higher number of blastomeres compared to those in non-treated groups in both small and large follicle groups. Besides that, = The increasing levels of acetylation of histone H3 at lysine 9 (H3K9) and methylation of histone H3 at lysine 4 (H3K4) in blastocyst derived from small and large antral follicle under the present of l-ascrobic acid lead to a significant positive effect on the developmental competence and improvement in quality of porcine embryos.

中文翻译：

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早熟培养法提高猪小窦卵泡卵母细胞发育能力

由于体外成熟 (IVM) 过程中的细胞质成熟不完全，来自小窦卵泡的卵母细胞到达囊胚的发育潜力较低。因此，我们开发了一种体外培养系统，用于来自小窦卵泡的猪卵母细胞在早熟（IVM 前）期间补充 l-抗坏血酸，以支持它们发育到囊胚阶段。除此之外，还将阐明 l-抗坏血酸如何影响猪卵母细胞的发育能力，特别关注组蛋白修饰。体外培养过程包括两个步骤。第一步是预 IVM 的 22 小时，第二步是 IVM 的 42 小时。我们在 IVM 前使用二丁酰环 AMP (dbcAMP) 和 L-抗坏血补充剂。根据这个程序的结果，我们提出了最好的培养条件，即在 IVM 前的最后 7 小时添加激素人绒毛膜促性腺激素 (hCG) 并继续培养以完成 IVM。我们观察到，在该培养系统中，经过 IVM 后，来自小卵泡的猪卵母细胞的减数分裂能力与来自大卵泡的卵母细胞的减数分裂能力一样高。此外，我们的研究表明，100 μg/mL 的 l-抗坏血酸补充剂显着增强了猪卵母细胞的发育潜力。有趣的是，用l-抗坏血酸处理的小窦卵泡的卵母细胞可以获得与大窦卵泡一样高的囊胚数量和质量。在小卵泡组和大卵泡组中，与未治疗组相比，治疗组的卵裂球数量显着增加。除此之外，