| 1. |
- Zhang, Hua, et al.
(författare)
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Combating ovarian aging depends on the use of existing ovarian follicles, not on putative oogonial stem cells
- 2013
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Ingår i: Reproduction. - : Bioscientifica. - 1470-1626 .- 1741-7899. ; 146:6
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Tidskriftsartikel (refereegranskat)abstract
- Ovarian aging is characterized by both a reduction in egg quality and a drastic reduction in the number of ovarian follicles. It has been generally accepted for 60 years that a fixed population of primordial follicles is established in the ovaries during early life, and in most mammalian species, oocytes cannot renew themselves in postnatal or adult life. This dogma, however, has been challenged over the past decade. In this review, we summarize the recent studies on primordial follicles and putative oogonial stem cells and discuss what resources in the ovary might be more reliable and promising source tools for combating ovarian aging.
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| 2. |
- Zhang, Hua, et al.
(författare)
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Experimental evidence showing that no mitotically active female germline progenitors exist in postnatal mouse ovaries
- 2012
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424. ; 109:31, s. 12580-12585
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Tidskriftsartikel (refereegranskat)abstract
- It has been generally accepted for more than half a century that, in most mammalian species, oocytes cannot renew themselves in postnatal or adult life, and that the number of oocytes is already fixed in fetal or neonatal ovaries. This assumption, however, has been challenged over the past decade. In this study, we have taken an endogenous genetic approach to this question and generated a multiple fluorescent Rosa26(rbw/+); Ddx4-Cre germline reporter mouse model for in vivo and in vitro tracing of the development of female germline cell lineage. Through live cell imaging and de novo folliculogenesis experiments, we show that the Ddx4-expressing cells from postnatal mouse ovaries did not enter mitosis, nor did they contribute to oocytes during de novo folliculogenesis. Our results provide evidence that supports the traditional view that no postnatal follicular renewal occurs in mammals, and no mitotically active Ddx4-expressing female germline progenitors exist in postnatal mouse ovaries.
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| 3. |
- Zheng, Wenjing, et al.
(författare)
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The two classes of primordial follicles in the mouse ovary: their development, physiological functions and implications for future research
- 2014
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Ingår i: Molecular Human Reproduction. - : Oxford University Press (OUP). - 1360-9947 .- 1460-2407. ; 20:4, s. 286-292
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Forskningsöversikt (refereegranskat)abstract
- Ovarian follicles are the basic functional units in the mammalian ovary. This review summarizes early pioneering studies and focuses on recent progress that has shown that there are two distinct classes of primordial follicles in the ovary: the first wave of primordial follicles that are activated immediately after they are formed and the adult primordial follicles that are activated gradually in later life. These two separate classes have been proposed for two decades, but sufficient experimental evidence to support this hypothesis has only been obtained recently using newly developed follicular tracing techniques in genetically modified mouse models. These two follicle populations differ from each other primarily in terms of their developmental dynamics and their contributions to ovarian physiology. It is apparent now that these two follicle populations should be treated separately, and such knowledge will hopefully lead to a more in-depth understanding of how distinct types of primordial follicles contribute to physiologic and pathologic alterations of the mammalian ovary.
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| 4. |
- Zheng, Wenjing, et al.
(författare)
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Two classes of ovarian primordial follicles exhibit distinct developmental dynamics and physiological functions.
- 2014
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Ingår i: Human Molecular Genetics. - : Oxford University Press (OUP). - 0964-6906 .- 1460-2083. ; 23:4, s. 920-928
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Tidskriftsartikel (refereegranskat)abstract
- In the mammalian ovary, progressive activation of primordial follicles serves as the source of fertilizable ova, and disorders in the development of primordial follicles lead to various ovarian diseases. However, very little is known about the developmental dynamics of primordial follicles under physiological conditions, and the fates of distinct populations of primordial follicles also remain unclear. In this study, by generating the Foxl2-CreERT2 and Sohlh1-CreERT2 inducible mouse models, we have specifically labeled and traced the in vivo development of two classes of primordial follicles, the first wave of simultaneously activated follicles after birth and the primordial follicles that are gradually activated in adulthood. Our results show that the first wave of follicles exists in the ovaries for ∼3 months and contributes to the onset of puberty and to early fertility. The primordial follicles at the ovarian cortex gradually replace the first wave of follicles and dominate the ovary after 3 months of age, providing fertility until the end of reproductive life. Moreover, by tracing the time periods needed for primordial follicles to reach various advanced stages in vivo, we were able to determine the exact developmental dynamics of the two classes of primordial follicles. We have now revealed the lifelong developmental dynamics of ovarian primordial follicles under physiological conditions and have clearly shown that two classes of primordial follicles follow distinct, age-dependent developmental paths and play different roles in the mammalian reproductive lifespan.
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