Nature：利用干细胞培育出人工精子卵子 美国科学家在实验室中通过人体干细胞制造出人工精子和卵子，在为无数不孕不 育症夫妇带来福音的同时，也为人类的亲子关系带来无穷争论。 这项研究由美国政府资助。加州斯坦福大学的科学家将化学药物和维生素混合， 成功诱使干细胞变成了精子和卵子。他们培育出的精子有头部和短小的尾部，被 认为发育成熟，完全能够使卵子受精。而卵子培育还处于研究初期，但仍然比其 他科学家取得的成果要进步得多。 精子和卵子的培育进展发表于《自然》杂志，为不孕症男女有朝一日培育出自己 的精卵用于试管婴儿疗法带来了希望。 美国的科研团队利用生长了几天的胚胎干细胞完成了实验，但他们希望进一步利 用人体表皮细胞复制精子和卵子的培育过程。表皮细胞将首先放入一种混合物中 ，该混合物会使表皮细胞的生物钟回溯到胚胎干细胞状态。然后再将其培育成精 子和卵子。而使用某人自己的皮肤意味着实验室培育出的精子或卵子不会与其身 体出现排斥反应。 未来的科学研究也可能会利用男性皮肤培育出“雄性卵子”，或者利用女性皮肤 培育出“雌性精子”。这将帮助同性恋夫妇拥有遗传学上的亲生子女。但是，很 多科学家质疑，由于女性细胞中缺少男性的Y染色体，因此从中培育出精子是不可 能的” 根据世界卫生组织公布的数字，全世界不孕症患者人数约为8000万—1.1亿，还有 很多育龄夫妇由于癌症治疗而无法生育。最新的实验成果会帮助他们 成功生育出 至少从生物学的角度是他们自己的子女。然而，这同时也引发了巨大的道德和伦 理争论，因为这可能会制作出完全的人工婴儿，众多男女也会逐渐退出哺 育后代 的行列。反对者认为肆意改变人类生育过程是错误的，并警告说治疗不育症的进 展有可能引发家庭成员关系的扭曲和破坏。（生物谷）
Chapter 2
The development of germ cells
一、生殖细胞
（一）精子发生和成熟
1. 睾丸中发生：
精原细胞——>初级精母细胞——>次级精母细胞 ——>精子细胞——>精子 结果：染色体数减半；DNA量减半； 核型为23, X 或23, Y
2. 附睾内成熟：获得运动和受精能力。


Journal of Molecular Cell Biology (2009), 1–11 doi:10.1093/jmcb/mjp026 Dazl Promotes Germ Cell Differentiation from Embryonic Stem Cells Zhuo Yu1, Ping Ji1, Jinping Cao1, Shu Zhu1, Yao Li2, Lin Zheng3, Xuejin Chen2, and Lixin Feng1,* 1 Laboratory for Germ Cell Research, Institute of Medical Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China 2 Department of Laboratory Animal Sciences, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China 3 Department of Pathology, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China It has been demonstrated that through the formation of embryoid bodies (EBs) germ cells can be derived from embryonic stem (ES) cells. Here, we describe a transgene expression approach to derive germ cells directly from ES cells in vitro without EB formation. Through the ectopic expression of Deleted in Azoospermia-Like (Dazl), a germ cell-specific RNA-binding protein,both motile tailed-sperm and oocytes were induced from mouse ES (mES) cells in culture. Furthermore, transient overexpression of Dazl led to suppression of Nanog but induced germ cell nuclear antigen in mES cells. Dazl knockdown resulted in reduction in the expression of germ cell markers including Stella, MVH and Prdm1. Our study indicates that Dazl is a master gene controlling germ cell differentiation and that ectopic expression of Dazl promotes the dynamic differentiation of mouse ES cells into gametes in vitro.


Nature advance online publication 28 October 2009 | doi:10.1038/nature08562 Human DAZL, DAZ and BOULE genes modulate primordial germ-cell and haploid gamete formation Kehkooi Kee1, Vanessa T. Angeles1, Martha Flores1, Ha Nam Nguyen1 & Renee A. Reijo Pera1 Center for Human Embryonic Stem Cell Research and Education, Institute for Stem Cell Biology & Regenerative Medicine, Department of Obstetrics and Gynecology, Stanford University School of Medicine, Stanford University, Palo Alto, California 94305, USA Correspondence to: Renee A. Reijo Pera1 Correspondence and requests for materials should be addressed to R.A.R.P. The leading cause of infertility in men and women is quantitative and qualitative defects in human germ-cell (oocyte and sperm) development. Yet, it has not been possible to examine the unique developmental genetics of human germ-cell formation and differentiation owing to inaccessibility of germ cells during fetal development. Although several studies have shown that germ cells can be differentiated from mouse and human embryonic stem cells, human germ cells differentiated in these studies generally did not develop beyond the earliest stages1, 2, 3, 4, 5, 6, 7, 8. Here we used a germ-cell reporter to quantify and isolate primordial germ cells derived from both male and female human embryonic stem cells. By silencing and overexpressing genes that encode germ-cell-specific cytoplasmic RNA-binding proteins (not transcription factors), we modulated human germ-cell formation and developmental progression. We observed that human DAZL (deleted in azoospermialike) functions in primordial germ-cell formation, whereas closely related genes DAZ and BOULE (also called BOLL) promote later stages of meiosis and development of haploid gametes. These results are significant to the generation of gametes for future basic science and potential clinical applications.
3. 女性生殖道内获能和顶体反应