2012年8月12日 訊 /生物谷BIOON/ --近日,，一項針對來自胚胎期的未成熟卵子（卵母細(xì)胞）起源的研究為科學(xué)界一直以來的爭議提供了新的信息,，由于女性生物鐘的原因，卵母細(xì)胞的數(shù)量隨著其年齡的增加而逐漸減少,，而且古代教條主義認(rèn)為，哺乳動物在產(chǎn)后其卵母細(xì)胞并不能夠自我更新?？窃诮盏膰H雜志PLoS Genetics上的一篇研究報告中，來自麻省總醫(yī)院和愛丁堡大學(xué)的研究者揭示了婦女在其成年生活中依然可以產(chǎn)生新的卵細(xì)胞,。
卵子是由處于有絲分裂周期的起源生殖細(xì)胞（或生殖祖細(xì)胞）所產(chǎn)生的,，生殖祖細(xì)胞通過細(xì)胞分裂結(jié)束了其增值的能力，最終進入減數(shù)分裂期,，單一的產(chǎn)生卵細(xì)胞和精子,。傳統(tǒng)觀念認(rèn)為雌性哺乳動物自出生以后就攜帶有畢生所有的卵細(xì)胞了，然而研究者的最新研究表明,，成年鼠和人類的卵巢存在有罕見的生殖祖細(xì)胞（稱為oogonial干細(xì)胞）,，其有能力分化并產(chǎn)生卵母細(xì)胞。
研究者使用了一種強大的遺傳工具來追蹤隨著年齡增長的細(xì)胞的分裂過程和數(shù)量,。如果傳統(tǒng)的觀念是正確的,，所有的細(xì)胞分裂應(yīng)該在出生之前都已經(jīng)發(fā)生了，因此所有的卵細(xì)胞應(yīng)該表現(xiàn)出相同的年齡深度,。然而研究結(jié)果恰恰相反,，隨著雌性小鼠的生長，卵細(xì)胞的年齡明顯增加了,。
盡管研究者的研究局限于小鼠之中,，但是也提供了明顯的證據(jù)揭示：oogonial干細(xì)胞同樣存在于生育年齡的婦女卵巢中，而且這些干細(xì)胞擁有完全的能力,，可以在實驗條件下產(chǎn)生新的卵細(xì)胞,。當(dāng)然后期研究者還會進行深入研究來提供更多的證據(jù)。（生物谷Bioon.com）
編譯自：Do ovaries continue to produce eggs during adulthood?
doi:10.1371/journal.pgen.1002848
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PMID:
Oocyte Family Trees: Old Branches or New Stems?
Dori C. Woods1,2, Evelyn E. Telfer3, Jonathan L. Tilly1,2*
The notion of a “biological clock” in women arises from the fact that oocytes progressively decline in number to the point of exhaustion as females get older, along with a decades-old dogmatic view that oocytes cannot be renewed in mammals after birth [1]. This latter thinking was challenged in 2004 when Tilly and colleagues [2], then others [3], reported that the rate of oocyte loss through follicular atresia and ovulation was much higher than the net rate of oocyte decline. This ignited an ongoing debate about whether the ovaries of adult mammals can form new oocytes and follicles [4]–[6]. Recent work demonstrating that oocyte-producing (oogonial) stem cells (OSCs; also referred to as female germline stem cells or fGSCs) exist in and can be isolated from ovaries of adult fish [7], [8], mice [2], [9]–[11], and even humans [11], [12] has led to new ideas about reproductive biological clocks. Earlier this year, a paper published in PLoS Genetics offered some of the most direct evidence to date that oogenesis in mice continues into adulthood under normal physiological conditions [13].
