Hunter Damien, Anand-Ivell Ravinder, Danner Sandra, Ivell Richard
Spermatogenesis. 2012 Jan 1;2(1):32-43. doi: 10.4161/spmg.19383.
Understanding the mechanisms that lead to the differentiation of male germ cells from their spermatogonial stem cells through meiosis to give rise to mature haploid spermatozoa has been a major quest for many decades. Unlike most other cell types this differentiation process is more or less completely dependent upon the cells being located within the strongly structured niche provided by mature Sertoli cells within an intact seminiferous epithelium. While much new information is currently being obtained through the application and description of relevant gene mutations, there is still a considerable need for in vitro models with which to explore the mechanisms involved. Not only are systems of in vitro spermatogenesis important for understanding the basic science, they have marked pragmatic value in offering ex vivo systems for the artificial maturation of immature germ cells from male infertility patients, as well as providing opportunities for the transgenic manipulation of male germ cells. In this review, we have summarized literature relating to simplistic culturing of germ cells, co-cultures of germ cells with other cell types, especially with Sertoli cells, cultures of seminiferous tubule fragments, and briefly mention the opportunities of xenografting larger testicular pieces. The majority of methods are successful in allowing the differentiation of small steps in the progress of spermatogonia to spermatozoa; few tolerate the chromosomal reduction division through meiosis, and even fewer seem able to complete the complex morphogenesis which results in freely swimming spermatozoa. However, recent progress with complex culture environments, such as 3-d matrices, suggest that possibly success is now not too far away.
几十年来，了解雄性生殖细胞从精原干细胞通过减数分裂分化为成熟单倍体精子的机制一直是一项主要的研究任务。与大多数其他细胞类型不同，这种分化过程或多或少完全依赖于细胞所处的由完整生精上皮内成熟支持细胞提供的高度结构化微环境。虽然目前通过相关基因突变的应用和描述获得了许多新信息，但仍然非常需要用于探索相关机制的体外模型。体外精子发生系统不仅对于理解基础科学很重要，它们在为男性不育患者的未成熟生殖细胞人工成熟提供体外系统方面具有显著的实用价值，同时也为男性生殖细胞的转基因操作提供了机会。在这篇综述中，我们总结了与生殖细胞的简单培养、生殖细胞与其他细胞类型（特别是与支持细胞）的共培养、生精小管片段的培养相关的文献，并简要提及了移植更大睾丸组织块的机会。大多数方法成功地实现了精原细胞向精子发育过程中的小步骤分化；很少有方法能耐受减数分裂过程中的染色体减数分裂，甚至更少的方法似乎能够完成导致自由游动精子的复杂形态发生过程。然而，最近在复杂培养环境（如三维基质）方面的进展表明，成功可能已为期不远。
