Mammalian fetal ovaries contain numerous primordial germ cells (PGCs), although few mature oocytes are obtained from females, owing to apoptosis and follicle atresia. The regulatory mechanisms underlying oogenesis/folliculogenesis remain unknown. Development of methods for obtaining mature oocytes from PGCs in fetal ovaries in vitro could contribute to clarifying these mechanisms. The failure of follicle assembly has been found to be the most challenging aspect in conventional culture conditions. Recently, we established novel culture conditions that enable successful follicle assembly, sustaining interactions between the oocyte and somatic cells, and, in turn, promoting oocyte growth and maturation. Mature oocytes were differentiated from PGCs after a 1-month culture period. A hundred mouse offspring were obtained from approximately a thousand mature oocytes, indicating that oocytes that were differentiated from PGCs in vitro acquired totipotency after fertilization. Here we provide a detailed protocol for using this in vitro system. This in vitro system will potentially provide a novel platform for studying oogenesis and preservation of female germ cells.

中文翻译：

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体外从有丝分裂生殖细胞发育可育小鼠卵母细胞。

哺乳动物的胎儿卵巢包含许多原始生殖细胞（PGC），尽管由于凋亡和卵泡闭锁，很少从雌性获得成熟的卵母细胞。卵子发生/卵泡发生的调节机制仍是未知的。体外从胎儿卵巢中的PGC获得成熟卵母细胞的方法的开发可能有助于阐明这些机制。已经发现卵泡组装的失败是常规培养条件下最具挑战性的方面。最近，我们建立了新颖的培养条件，能够成功完成卵泡组装，维持卵母细胞和体细胞之间的相互作用，进而促进卵母细胞的生长和成熟。经过1个月的培养后，成熟的卵母细胞与PGC分化。从大约一千个成熟的卵母细胞中获得了一百只小鼠后代，这表明在体外受精后与PGCs分化的卵母细胞具有全能性。在这里，我们提供了使用此体外系统的详细协议。该体外系统将可能为研究雌性生殖细胞的发生和保存提供一个新颖的平台。