生物谷报道：中山大学和美国南佛罗里达大学的研究人员表示，年老妇女产生新卵子几乎不可能。
这项新的研究结果发表于2007年3月的Developmental Biology期刊中，且于4月26日的Nature中提出对于该项研究的评论。这项研究的结果反驳了哈佛的Jonathan Tilly博士的研究小组所获得的具争议性之发现。
Tilly 的研究结果发表在2004年的Nature中，2005年又在Cell中发布了一篇后续研究结果。他的研究结果挑战了生物学的一条基本定律，即包括女人在内的哺乳动物与生俱来只有一定的生命期间产生卵子。Tilly的研究组发现干细胞能够从骨髓迁移到小鼠卵巢并产生新的卵子。
此后，其它的一些研究论文反驳了Tilly的惊人发现：小鼠终身能产生新卵子。现在，南佛罗里达州大学的David Keefe博士和在中山大学任职的同事Lin Liu证实，没有证据显示妇女在出生后可以产生新卵子的假说。
研究人员在从12名年龄在28到53岁的妇女获得的卵巢细胞活组织切片中，搜寻干细胞或者减数细胞分裂的标志。
虽然研究人员使用了最灵敏的方法，但始终未发现人类卵巢中有任何卵子干细胞存在的证据。这表明，Tilly在小鼠中的发现不能推及到人类身上。
Keefe解释说，Tilly博士可能看到的只是很像卵子的非卵子细胞；另外一种解释就是由于小鼠卵子比人类妇女卵子更具弹性，因此小鼠身上的发现不适用于妇女。
研究人员表示，这项研究非常重要，因为它肯定了对妇女产生卵子问题的经典定律。生育学传统观点认为，妇女出生时就已经形成了她这一生中所有的卵子，在每次排卵过程中被一个一个释放。而到了更年期，卵巢里几乎没有成熟卵子存在。
（编译/姜欣慧） (资料来源 : biocompare)
英文原文：
No Evidence Older Women Generate New Eggs
5/8/2007
Source: University of South Florida Health
It is highly unlikely that older women generate new eggs, report researchers at the University of South Florida in collaboration with a center in China.
The USF study, published in the March 2007 issue of the journal Developmental Biology and highlighted April 26, 2007 in Nature, counters the controversial findings of reproductive endocrinologist Jonathan Tilly, PhD, and his team of Harvard scientists. Tilly’s work, published in 2004 in Nature with a follow-up study a year later in Cell, challenged the biological dogma that mammals, including women, are born with a limited lifetime supply of eggs. Tilly reported the discovery of stem cells capable of migrating from bone marrow to mouse ovaries and generating new eggs there. The research fueled hopes that a new treatment – such as bone marrow transplantation – might one day help older women regain their fertility.
Since then, other papers have refuted Tilly’s surprising finding that mice can produce eggs throughout their lives. Now, David Keefe, MD, professor and chair of Obstetrics and Gynecology at USF, and colleague Lin Liu, who also holds a post at Sun Yat-Sen University in Guangzhou, China, say they can find no evidence to support his hypothesis that women may generate new eggs after birth.
The USF researchers searched for markers of stem cells or of meiotic cell division in ovarian cells biopsied from 12 women between the ages of 28 and 53.
“Despite using the most sensitive methods available, we found no evidence of any egg stem cells in human ovaries, demonstrating that Dr. Tilly’s findings in mice do not apply to women,” Dr. Keefe said. “Dr. Tilly likely was seeing non-egg cells which resemble eggs. Another reason his findings do not apply to women could be because mice eggs are more resilient than women’s eggs. The bottom line is that women should not expect stem cell therapy to treat egg infertility or menopause in the foreseeable future.”
“This is a very important finding by a distinguished group of researchers and clinician-scientists at USF Health which affirms the traditional dogma of a finite period of fertility in women,” said Abdul S. Rao, MD, MA, DPhil, senior associate vice president for USF Health and vice dean for research and graduate affairs at the College of Medicine.
The traditional view of fertility holds that women are born with all their eggs and they are released one by one (occasionally two) at each ovulation. At menopause, few to no mature eggs are believed to remain in the ovaries.
- USF Health -
USF Health is a partnership of the University of South Florida’s colleges of medicine, nursing, and public health; the schools of basic biomedical sciences and physical therapy & rehabilitation sciences; and the USF Physicians Group. It is a partnership dedicated to the promise of creating a new model of health and health care. One of the nation’s top 63 public research universities as designated by the Carnegie Foundation for the Advancement of Teaching, USF received more than $310 million in research contracts and grants last year. It is ranked by the National Science Foundation as one of the nation’s fastest growing universities for federal research and development expenditures.
