Uptake of Tritiated Thymidine by Primordial Germinal Cells in the Ovaries of the Adult Slender Loris

Dávid, Gyula; Kumar, T. C. Anand; Baker, T. G.

doi:10.1530/jrf.0.0410447

Cited by 35 publications

(25 citation statements)

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“…The dynamics of oocyte over production in L. maximus by suppressing apoptosis, the persistence of PGC in the adult mouse ovary (Johnson et al 2004), and the detection of oogonial division and DNA synthesis in the ovaries of lorises (David et al 1974) clearly indicate that mammals display more variability and strategies for oocyte production than previously thought.…”

Section: Suppressed Apoptosis In the Manmalian Ovarymentioning

confidence: 89%

“…The absence of persistence of PGC was recently questioned by the finding of a small PGC population in the ovary of adult laboratory mice (Johnson et al 2004). Similarly, oocyte replenishing in adult life has also been observed in the mature ovaries from prosimian species of the genus Loris (David et al 1974). Abolition of apoptosis and germ cell demise in L. maximus challenges the postulate of massive germ cell exhaustion through PCD in the mammalian ovary, contradicting too the decades-old tenet.…”

Section: Suppressed Apoptosis In the Manmalian Ovarymentioning

confidence: 99%

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Naturally suppressed apoptosis prevents follicular atresia and oocyte reserve decline in the adult ovary of Lagostomus maximus (Rodentia, Caviomorpha)

Jensen

Willis²,

Albamonte³

et al. 2006

Reproduction

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It has been widely accepted that mammalian females are born with a non-renewing, finite pool of oocytes that will be continuously cleared by atresia, with only a small proportion of them reaching ovulation. Apoptosis regulates this mass germ cell death, especially through the balance between pro-and anti-apoptotic proteins encoded by the BCL-2 gene family. The caviomorph rodent Lagostomus maximus, the South American plains viscacha, displays the highest ovulation rate known for a mammal releasing 400-800 eggs per cycle. We tested the hypothesis that in L. maximus massive polyovulation is a consequence of reduced apoptosis resulting in suppressed follicular atresia. We found that anti-apoptotic BCL-2 gene is markedly expressed in all kind of follicles from primordial to fully mature antral stages in the adult ovary of L. maximus. On the other hand, pro-apoptotic BAX gene showed weak signals or was undetectable by immunohistochemical examination. Western blot against both proteins confirmed immunohistochemical results. Screening for DNA fragmentation by TUNEL assay was conspicuously negative in ovaries from both pregnant and non-pregnant females. In addition, a-oestrogen receptor also showed an enhanced expression from primordial stage to fully mature antral follicles. Our results show that natural preferential expression of BCL-2 and restricted BAX expression greatly suppresses apoptosis in the ovary of L. maximus. This prevents the decline of the oocyte reserve by abolishing follicular atresia and enables the highest ovulation rate known for a mammal, 400-800 or more eggs per cycle.

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Section: Suppressed Apoptosis In the Manmalian Ovarymentioning

confidence: 89%

Section: Suppressed Apoptosis In the Manmalian Ovarymentioning

confidence: 99%

Naturally suppressed apoptosis prevents follicular atresia and oocyte reserve decline in the adult ovary of Lagostomus maximus (Rodentia, Caviomorpha)

Jensen

Willis²,

Albamonte³

et al. 2006

Reproduction

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“…However, this proposal is a matter of current debate with different studies presenting evidence claiming for and against the existence of de novo oogenesis (Tilly et al 2009, Gougeon 2010. De novo oogenesis has been reported in several species of lorises (Butler & Juma 1970, David et al 1974 in which nests of dividing oogonia persist in the adult ovary. It has been claimed that this may represent an isolated phenomenon of some prosimian species as such germ cell nests do not seem to occur in the adult ovary in rodents (Kerr et al 2006).…”

Section: Discussionmentioning

confidence: 99%

Quantification of healthy and atretic germ cells and follicles in the developing and post-natal ovary of the South American plains vizcacha, Lagostomus maximus: evidence of continuous rise of the germinal reserve

et al. 2014

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The female germ line in mammals is subjected to massive cell death that eliminates 60–85% of the germinal reserve by birth and continues from birth to adulthood until the exhaustion of the germinal pool. Germ cell demise occurs mainly through apoptosis by means of a biased expression in favour of pro-apoptotic members of theBCL2gene family. By contrast, the South American plains vizcacha,Lagostomus maximus, exhibits sustained expression of the anti-apoptoticBCL2gene throughout gestation and a low incidence of germ cell apoptosis. This led to the proposal that, in the absence of death mechanisms other than apoptosis, the female germ line should increase continuously from foetal life until after birth. In this study, we quantified all healthy germ cells and follicles in the ovaries ofL. maximusfrom early foetal life to day 60 after birth using unbiased stereological methods and detected apoptosis by labelling with TUNEL assay. The healthy germ cell population increased continuously from early-developing ovary reaching a 50 times higher population number by the end of gestation. TUNEL-positive germ cells were <0.5% of the germ cell number, except at mid-gestation (3.62%). Mitotic proliferation, entrance into prophase I stage and primordial follicle formation occurred as overlapping processes from early pregnancy to birth. Germ cell number remained constant in early post-natal life, but a remnant population of non-follicular VASA- and PCNA-positive germ cells still persisted at post-natal day 60.L. maximusis the first mammal so far described in which female germ line develops in the absence of constitutive massive germ cell elimination.Free Spanish abstractSpanish translation of this abstract is freely available athttp://www.reproduction-online.org/content/147/2/199/suppl/DC1

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“…Our findings are in broad agreement with this interpretation. Oogenesis leading to the formation of new oocytes has been reported in immature and adult ovaries of several primate species (Duke 1967, Ioannu 1967, Butler & Juma 1970, David et al 1974.…”

Section: Discussionmentioning

confidence: 99%

“…The notion of a fixed, non-renewable reserve of primordial follicles has been questioned by several earlier studies of primate species, where in adult ovaries mitotically active germ cells in nests or single oogonia have been reported (Vermande-van Eck 1956, Duke 1967, Ioannou 1967, Butler & Juma 1970, David et al 1974. Adult ovaries of Drosophila contain germline stem cells that renew oocyte supply (Lin & Spradling 1995, Deng & Lin 2001, Wang & Lin 2004.…”

Section: Introductionmentioning

confidence: 99%

Quantification of healthy follicles in the neonatal and adult mouse ovary: evidence for maintenance of primordial follicle supply

Kerr¹,

Duckett²,

Myers³

et al. 2006

Reproduction

195

180

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Proliferation and partial meiotic maturation of germ cells in fetal ovaries is believed to establish a finite, non-renewable pool of primordial follicles at birth. The supply of primordial follicles in postnatal life should be depleted during folliculogenesis, either undergoing atresia or surviving to ovulation. Recent studies of mouse ovaries propose that intra-and extraovarian germline stem cells replenish oocytes and form new primordial follicles. We quantified all healthy follicles in C57BL/6 mouse ovaries from day 1 to 200 using unbiased stereological methods, immunolabelling of oocyte meiosis (germ cell nuclear antigen (GCNA)) and ovarian cell proliferation (proliferating cell nuclear antigen (PCNA)) and electronmicroscopy. Day 1 ovaries contained 7924G1564 (S.E.M.) oocytes or primordial follicles, declining on day 7 to 1987G203, with 200-800 oocytes ejected from individual ovaries on that day and day 12. Discarded oocytes and those subjacent to the surface epithelium were GCNA-positive indicating their incomplete meiotic maturation. From day 7 to 100 mean numbers of primordial follicles per ovary were not significantly depleted but declined at 200 days to 254G71. Mean numbers of all healthy follicles per ovary were not significantly different from day 7 to 100 (range 2332G349-3007G322). Primordial follicle oocytes were PCNA-negative. Occasional unidentified cells were PCNA-positive with mitotic figures observed in the cortex of day 1 and 12 ovaries. Although we found no evidence for ovarian germline stem cells, our data support the hypothesis of postnatal follicle renewal in postnatal and adult ovaries of C57BL/6 mice. Reproduction (2006) 132 95-109

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Uptake of Tritiated Thymidine by Primordial Germinal Cells in the Ovaries of the Adult Slender Loris

Cited by 35 publications

References 1 publication

Naturally suppressed apoptosis prevents follicular atresia and oocyte reserve decline in the adult ovary of Lagostomus maximus (Rodentia, Caviomorpha)

Naturally suppressed apoptosis prevents follicular atresia and oocyte reserve decline in the adult ovary of Lagostomus maximus (Rodentia, Caviomorpha)

Quantification of healthy and atretic germ cells and follicles in the developing and post-natal ovary of the South American plains vizcacha, Lagostomus maximus: evidence of continuous rise of the germinal reserve

Quantification of healthy follicles in the neonatal and adult mouse ovary: evidence for maintenance of primordial follicle supply

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