Hammond Memorial Lecture

Thibault, C.

doi:10.1530/jrf.0.0510001

Cited by 159 publications

(6 citation statements)

References 55 publications

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“…When cytoplasmic maturation is not completed, oocytes fail to undergo fertilization and early embryo development [41], [42]. To confirm that normal cytoplasmic maturation was completed, parthenogenetic activation was performed using Sr 2+ to stimulate the MII oocytes after Gas6 RNAi treatment.…”

Section: Resultsmentioning

confidence: 99%

Gas6 Downregulation Impaired Cytoplasmic Maturation and Pronuclear Formation Independent to the MPF Activity

Kim

et al. 2011

PLoS ONE

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Previously, we found that the growth arrest-specific gene 6 (Gas6) is more highly expressed in germinal vesicle (GV) oocytes than in metaphase II (MII) oocytes using annealing control primer (ACP)-PCR technology. The current study was undertaken to investigate the role of Gas6 in oocyte maturation and fertilization using RNA interference (RNAi). Interestingly, despite the specific and marked decrease in Gas6 mRNA and protein expression in GVs after Gas6 RNAi, nuclear maturation including spindle structures and chromosome segregation was not affected. The only discernible effect induced by Gas6 RNAi was a change in maturation promoting factor (MPF) activity. After parthenogenetic activation, Gas6 RNAi-treated oocytes at the MII stage had not developed further and arrested at MII (90.0%). After stimulation with Sr2+, Gas6-silenced MII oocytes had markedly reduced Ca2+ oscillation and exhibited no exocytosis of cortical granules. In these oocytes, sperm penetration occurred during fertilization but not pronucleus (PN) formation. By roscovitine and colcemid treatment, we found that the Gas6 knockdown affected cytoplasmic maturation directly, independent to the changed MPF activity. These results strongly suggest that 1) the Gas6 signaling itself is important to the cytoplasmic maturation, but not nuclear maturation, and 2) the decreased Gas6 expression and decreased MPF activity separately or mutually influence sperm head decondensation and PN formation.

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Section: Resultsmentioning

confidence: 99%

Gas6 Downregulation Impaired Cytoplasmic Maturation and Pronuclear Formation Independent to the MPF Activity

Kim

et al. 2011

PLoS ONE

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“…It has long been known that oogenesis and folliculogenesis are inextricably linked with the oocyte growing and developing in an intimate and mutually dependent relationship with the somatic cells of the follicle (Thibault 1977). During the course of folliculogenesis, oocytes first acquire meiotic competence and then gradually acquire developmental competence -a biochemical and molecular state that allows a mature oocyte to undergo normal fertilisation, support normal preimplantation embryo development and subsequent healthy growth of the implanted embryo to term (Hyttel et al 1997).…”

Section: Follicle-oocyte Interactionsmentioning

confidence: 99%

Regulation of folliculogenesis and the determination of ovulation rate in ruminants

Scaramuzzi

Baird

Campbell

et al. 2011

Reprod. Fertil. Dev.

253

213

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The paper presents an update of our 1993 model of ovarian follicular development in ruminants, based on knowledge gained from the past 15 years of research. The model addresses the sequence of events from follicular formation in fetal life, through the successive waves of follicular growth and atresia, culminating with the emergence of ovulatory follicles during reproductive cycles. The original concept of five developmental classes of follicles, defined primarily by their responses to gonadotrophins, is retained: primordial, committed, gonadotrophin-responsive, gonadotrophin-dependent and ovulatory follicles. The updated model has more extensive integration of the morphological, molecular and cellular events during folliculogenesis with systemic events in the whole animal. It also incorporates knowledge on factors that influence oocyte quality and the critical roles of the oocyte in regulating follicular development and ovulation rate. The original hypothetical mechanisms determining ovulation rate are retained but with some refinements; the enhanced viability of gonadotrophin-dependent follicles and increases in the number of gonadotrophin-responsive follicles by increases in the throughput of follicles to this stage of growth. Finally, we reexamine how these two mechanisms, which are thought not to be mutually exclusive, appear to account for most of the known genetic and environmental effects on ovulation rate.

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“…It was thought that BN oocytes could not be fully matured in the culture media used in this study [26]. However, the number of oocytes collected from ovaries after injection of PMSG was significantly higher than the number of oocytes that ovulated by induction of superovulation (Fig.…”

Section: Discussionmentioning

confidence: 84%

“…However, the development into offspring of the oocytes that underwent IVM after fertilization was not successful (Tables 4 and 5). This may be caused by the incomplete cytoplasmic maturation of the oocyte [26]. Miki et al .…”

Section: Discussionmentioning

confidence: 99%

<i>In vitro</i> maturation of immature rat oocytes under simple culture conditions and subsequent developmental ability

Taketsuru

Kaneko

2016

Journal of Reproduction and Development

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Rat oocytes can be produced artificially by superovulation. Because some strains show low sensitivity to superovulation treatment, in vitro maturation is an alternative method to produce numerous matured oocytes. Furthermore, establishment of an in vitro maturation system with simple culture conditions is cost effective and leads to easy handling of oocytes. This study examined developmental ability of rat germinal vesicle (GV) oocytes maturing in vitro under simple culture conditions. Significantly different numbers of ovulated oocytes reached the second metaphase of meiosis (MII) among Jcl:Wistar (17.0), F344/Stm (31.0), and BN/SsNSlc (2.2) rats in whom superovulation was induced by pregnant mare serum gonadotropin (PMSG) and human chorionic gonadotropin. However, similar numbers of GV oocytes were obtained from ovaries of PMSG-injected Wistar (27.7), F344 (34.7), and BN (24.7) rats. These GV oocytes were cultured in vitro in HTF, αMEM, and a 1:1 HTF + αMEM or TYH + αMEM mixture. High proportions of Wistar and F344 oocytes that matured to MII in αMEM were parthenogenetically activated by strontium chloride treatment (78% and 74%, respectively). Additionally, 10% of matured oocytes of both strains developed into offspring after intracytoplasmic sperm injection and embryo transfer to foster mothers. Although BN oocytes cultured in αMEM could be parthenogenetically activated and developed into offspring, the success rate was lower than that for Wistar and F344 oocytes. This study demonstrated that numerous GV oocytes were produced in rat ovaries by PMSG injection. This simple in vitro maturation system of immature oocytes could be further developed to maintain valuable rat strains experiencing reproductive difficulties.

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Hammond Memorial Lecture

Cited by 159 publications

References 55 publications

Gas6 Downregulation Impaired Cytoplasmic Maturation and Pronuclear Formation Independent to the MPF Activity

Gas6 Downregulation Impaired Cytoplasmic Maturation and Pronuclear Formation Independent to the MPF Activity

Regulation of folliculogenesis and the determination of ovulation rate in ruminants

<i>In vitro</i> maturation of immature rat oocytes under simple culture conditions and subsequent developmental ability

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