During the reproductive lifespan of a female, only a limited quantity of oocytes are naturally ovulated; therefore, the mammalian ovary possesses a substantial population of preantral follicles available to be handled and explored in vitro. Hence, the manipulation of preantral follicles enclosed in ovarian tissue aims to recover a considerable population of oocytes of high-value animals for potential application in profitable assisted reproductive technologies (ARTs). For this purpose, the technique of preantral follicle in vitro culture (IVC) has been the most common research tool, achieving extraordinary results with offspring production in the mouse model. Although promising outcomes have been generated in livestock animals after IVC of preantral follicles, the quantity and quality of embryo production with those oocytes are still poor. In recent years, the mare has become an additional model for IVC studies due to remarkable similarities with women and livestock animals regarding in vivo and in vitro ovarian folliculogenesis. For a successful IVC system, several factors should be carefully considered to provide an optimum culture environment able to support the viability and growth of preantral follicles enclosed in ovarian tissue. The cryopreservation of the ovarian tissue is another important in vitro manipulation technique that has been used to preserve the reproductive potential in humans and, in the future, may be used in highly valuable domestic animals or endangered species. Several improvements in cryopreservation protocols are necessary to support the utilization of ovarian tissue of different species in follow-up ARTs (e.g., ovarian fragment transplantation). This review aims to provide an update on the most current advances regarding supportive in vitro techniques used in equids to evaluate and manipulate preantral follicles and ovarian tissue, as well as methodological approaches used during IVC and cryopreservation techniques.

中文翻译：

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研究马卵巢组织体外培养和冷冻保存效率的支持技术：综述

在女性的生殖生命周期中，自然排卵的卵母细胞数量有限；因此，哺乳动物卵巢拥有大量可在体外处理和探索的腔前卵泡。因此，对封闭在卵巢组织中的窦前卵泡的操作旨在恢复大量高价值动物的卵母细胞，以用于有利可图的辅助生殖技术 (ART) 的潜在应用。为此，腔前卵泡体外培养 (IVC) 技术已成为最常见的研究工具，在小鼠模型中产生后代取得了非凡的成果。尽管在腔前卵泡 IVC 后在家畜动物中产生了有希望的结果，但这些卵母细胞的胚胎产生的数量和质量仍然很差。近年来，由于与女性和家畜动物在体内和体外卵巢卵泡发生方面的显着相似性，母马已成为 IVC 研究的另一个模型。对于成功的 IVC 系统，应仔细考虑几个因素，以提供能够支持封闭在卵巢组织中的窦前卵泡的活力和生长的最佳培养环境。卵巢组织的冷冻保存是另一种重要的体外操作技术，已被用于保存人类的生殖潜力，将来可能用于高价值的家畜或濒危物种。需要对冷冻保存方案进行一些改进，以支持在后续 ART（例如，卵巢碎片移植）中利用不同物种的卵巢组织。