Department of Public Health and Cell Biology, Section of Histology and Embryology, University of Rome Tor Vergata, Via Montpellier 1, Rome 00173, Italy.
Mol Hum Reprod. 2010 Sep;16(9):632-6. doi: 10.1093/molehr/gaq006. Epub 2010 Jan 19.
At or early after birth, mammalian ovaries are filled with primordial follicles each composed by an oocyte blocked at the end of prophase I surrounded by a single layer of granulosa cells. The doctrine that female mammals are born with a finite number of oocytes fated to be exhausted with the age has been challenged by recent results claiming that new oocytes can be continuously formed in the post-natal mouse ovary. In my view, this notion, termed neo-oogenesis, is strictly linked to the process of the germline specification which presents unique features. Therefore, in the present paper, I am going to discuss two aspects of neo-oogenesis related to this process: first, evidence showing that adult mammalian ovary contains cells able to undergo germline specification and produce new oocytes; and second, the possible origin of such cells. In conclusion, I favour the possibility that a small number of primordial germ cells (PGCs)/oogonia or of PGC-derived undifferentiated cells with stem cell characteristics could remain in the post-natal ovary and under certain conditions may resume mitosis, enter meiosis and give rise to oocytes.
在出生时或出生后不久，哺乳动物的卵巢中充满了原始卵泡，每个原始卵泡由一个在第一次减数分裂末期被阻断的卵母细胞组成，周围是一层颗粒细胞。女性哺乳动物一生的卵母细胞数量是有限的，这一观点随着最近的研究结果而受到挑战，这些研究结果表明，新生的卵母细胞可以在产后的小鼠卵巢中不断形成。在我看来，这种被称为新卵发生的观点与生殖系特化过程密切相关，生殖系特化过程具有独特的特征。因此，在本文中，我将讨论与该过程相关的新卵发生的两个方面：首先，证明成年哺乳动物卵巢中存在能够进行生殖系特化并产生新卵母细胞的细胞；其次，这些细胞的可能起源。总之，我倾向于认为，一小部分原始生殖细胞（PGC）/卵原细胞或具有干细胞特征的 PGC 衍生的未分化细胞可能会留在产后卵巢中，并在某些条件下可能恢复有丝分裂、进入减数分裂并产生卵母细胞。
