2015考研英语阅读45岁也能生娃

　　Life begins at 45

　　45岁也能生娃

　　Hope for older mothers.

　　高龄母亲的福音。

　　WHEN it comes to reproduction, men have iteasy. Almost to the end of their lives most have anample supply of sperm. Women are not so lucky.They are born with a supply of eggs that typically runs out when they reach middle age. Thatcould be about to change, however. Researchers have confirmed that women harbourovarian stem cells, and that these can give rise to new eggs.

　　讲到繁衍，男人表示压力很小。大多数人直到去世前都拥有充足的精子。女人可就没这么幸运了。人到中年，她们就会耗尽出生时携带的卵子。不过，这一情形很快就能得到改变。研究者们证实，女人拥有卵巢干细胞，而这种细胞能成为新的卵细胞的来源。

　　Stem cells have the ability to divide continuously and to change into different types of cells.Stem cells from adults can produce a variety of cell types, in addition to those that makeup the tissue in which they are found.

　　干细胞具有不断分裂的潜力，可以分化成许多种类的细胞。成人干细胞不仅可以分化成其来源组织的细胞，还能分化成其它细胞。

　　In 2004 Jonathan Tilly of Harvard Medical School and his colleagues discovered stem cells inmouse ovaries. Since then it has been shown that these ovarian stem cells can develop intoeggs, be fertilised and produce perfectly healthy mouse pups. But researchers have beenreluctant to believe that something similar might be possible in humans.

　　2004年，哈弗医学院的Jonathan Tilly及其同事在老鼠卵巢里发现了干细胞。迄今已经证实，此类卵巢干细胞能够分化成为卵细胞，卵细胞在受精后还能发育成健康的鼠宝宝。但是研究者尚不能确信人类也存在类似机能。

　　Proving that this was indeed the case was tricky. Human ovarian tissue-especially fromyoung, healthy donors-is not easy to come by. Dr Tilly s breakthrough came when hediscovered that a former colleague, Yasushi Takai of Saitama Medical University in Japan,had in his freezer healthy ovarian tissue from 30 patients who had changed sex.

　　想要弄清真相有些困难。人类卵巢组织很难找到，健康的年轻捐献者的组织更难寻觅。幸而Tilly博士发现他的前同事日本埼玉医科大学的Yasushi Takai在冰箱里存放了30个变性人不再需要的健康卵巢组织，取得了突破。

　　Using a sophisticated cell-sorting technique, the researchers developed a way to identifyovarian stem cells that works for both mice and humans. Then they took the human ovarianstem cells, labelled them with a green fluorescent protein and put them back into a slice ofhuman ovary . The glowing green cells soon produced a brand new crop of human eggs, accordingto their findings published this week in Nature Medicine.

　　研究人员运用尖端的细胞分选技术，找出方法，证实人类和老鼠身上都存在卵巢干细胞。随后，他们分离出人类卵巢干细胞，用荧光蛋白做上标记再把它植入一片人类卵巢组织。这片组织被移植到了活鼠体内，使其保持正常卵巢的机能。他们本周发表在《自然医学》上的结果称，这些绿芒闪烁的细胞很快制造出了一批人类卵细胞。

　　Offshoring fertilisation.

　　国外受精。

　　Fertilising these eggs for experimentation is forbidden in America. Britain s HumanFertilisation and Embryology Authority, however, will allow it in certain cases. So nextmonth Dr Tilly will take some of his stem cell booty to Edinburgh to collaborate with EvelynTelfer, who has developed a technique for growing human eggs from an early stage. Sheholds a licence to fertilise them experimentally.

　　美国禁止为实验用的卵细胞受精，不过英国的人类受精和胚胎学管理局将在某些研究中允许给卵细胞授精。所以，下个月Tilly博士将带着卵细胞去爱丁堡与Evelyn Telfer合作。Evelyn Telfer掌握了用卵母细胞培育卵细胞的技术，持有给试验用细胞授精的许可。

　　The discovery could revolutionise infertility treatment for women in several ways. For onething, research has shown that in mice, even aged ovaries contain ovarian stem cells. Andwhen those stem cells are placed into a young ovary, they will develop healthy eggs. Thisraises the possibility that, one day, women of advanced age could have their ownbiologically related children. Currently, many women over 45 have to make do with in-vitrofertilisation using the egg of a younger woman.

　　这项发现会是女性不育症治疗的一场革命。一方面，老鼠体内衰老的卵巢里也有卵巢干细胞;将这些细胞移植到年轻的卵巢中后，它们能制造健康的卵子。这意味着将来的某天，年龄较大的妇女也能拥有生物学意义上的自己的孩子。目前，许多45岁以上的妇女只能凑合着用年轻女人的卵细胞进行体外受精。

　　Other treatments will become available sooner. OvaScience, a fertility company based inBoston which has exclusive rights to exploit Dr Tilly s research on mammalian ovarianstem cells, will begin offering a novel treatment in July. This uses a woman s own stem cellsto provide her eggs with extra energy by creating fresh mitochondria-sub-units that existwithin cells and supply them with energy. They too can become scarcer and less productivewith age. Previous studies have shown that boosting mitochondria can dramatically increasethe success rates of IVF. When it comes to reproduction, men will still have it easier forsome time. But women are catching up.

　　另一种疗法也将很快得到应用。波士顿的OvaScience公司独家开发Tilly博士的哺乳动物卵巢干细胞细胞研究。今年7月，该公司将开始提供一种全新的疗法：使用卵巢干细胞制造线粒体，给妇女的卵细胞增添活力。线粒体的数量和活力也会随着年龄增长而递减。此前的研究表明，增加线粒体数量能极大提高体外受精的成功率。谈起繁衍来，男人还能优哉游哉一阵子。不过，女人即将迎头赶上。