Maturation of Mammalian Oocytes in Vitro

Skoblina, M. N.

doi:10.1007/978-1-4684-0682-5_5

Cited by 5 publications

(2 citation statements)

References 257 publications

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“…However, germinal vesicle-stage, cumulus cell-enclosed oocytes can be blocked in prophase I if the medium is supplemented with purines or cAMP-elevating agents [1][2][3][4]. This meiotic arrest can be alleviated by stimulatory ligands such as FSH and epidermal growth factor that act on the surrounding cumulus cells to generate a signal that triggers germinal vesicle breakdown (GVB) despite the presence of meiotic inhibitor [5,6].…”

Section: Introductionmentioning

confidence: 99%

Meiotic Induction in Cumulus Cell-Enclosed Mouse Oocytes: Involvement of the Pentose Phosphate Pathway1

Downs¹,

Humpherson²,

Leese³

1998

Biology of Reproduction

128

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In this study we tested the hypothesis that the pentose phosphate pathway (PPP) participates in the meiotic induction of mouse oocytes. The electron acceptors methylene blue, phenazine ethosulfate (PES), and pyrroline-5-carboxylate (P5C) oxidize NADPH to NADP and activate the NADP-dependent enzymes of the PPP. Each of these compounds triggered a dose-dependent increase in meiotic maturation in hypoxanthine-arrested cumulus cell-enclosed oocytes during 17- to 18-h cultures. More than 96% of the oocytes underwent germinal vesicle breakdown (GVB) at the highest concentrations of P5C and PES tested (250 and 1 microM, respectively) as compared to only 45-52% of control oocytes. P5C was also stimulatory to denuded oocytes. Analysis of energy substrates in microdrop cultures revealed a 3.6-fold increase in glucose consumption by PES-treated oocyte-cumulus cell complexes that was associated with stimulation of GVB. On the other hand, 2-deoxyglucose, which interferes with glucose utilization, prevented the induction of maturation brought about by P5C. Apocynin and diphenyleneiodonium, inhibitors of NADPH oxidase, prevented meiotic maturation in the presence or absence of FSH. Gonadotropin-induced maturation was also prevented by 6-aminonicotinamide (6-AN) and dehydroepiandrosterone (DHEA), inhibitors of the two NADP-dependent enzymes of the PPP, and this was accompanied by suppression of glucose consumption. Phosphoribosyl-pyrophosphate (PRPP) is an important compound required in purine metabolism and can be formed from the end product of the oxidative arm of the PPP, ribose-5-phosphate. Ribose, which can be metabolized to PRPP, increased PRPP synthesis in complexes and induced meiotic maturation when added to hypoxanthine-arrested cumulus cell-enclosed oocytes in glucose-free medium in both the presence and absence of FSH. PRPP levels within complexes were also increased by glucose and FSH, but were reduced by hypoxanthine, 6-AN, and DHEA. In addition, exogenous PRPP stimulated maturation in hypoxanthine-arrested oocytes. These results support the proposition that glucose metabolism through the PPP is important in the meiotic induction mechanism and may involve the generation of PRPP that acts, at least in part, through the purine metabolizing pathways.

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Section: Introductionmentioning

confidence: 99%

Meiotic Induction in Cumulus Cell-Enclosed Mouse Oocytes: Involvement of the Pentose Phosphate Pathway1

Downs¹,

Humpherson²,

Leese³

1998

Biology of Reproduction

128

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“…This metabolic coupling is essential for normal growth of the oocyte and for maintenance of meiotic arrest (Moor and Cran, 1980;Brower and Schultz, 1982). In the cow these heterologous contacts are also important during final maturation (Skoblina, 1988). This is demonstrated by the fact that the proportion of oocytes that mature is lower if oocytes are denuded before final maturation (Fukui and Sakuma, 1980).…”

Section: Introductionmentioning

confidence: 99%

Heterologous cell contacts and metabolic coupling in bovine cumulus oocyte complexes

Loos

Kastrop

Maurik

et al. 1991

Molecular Reproduction Devel

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The integrity of the cumulus cell processes were studied in four categories of bovine cumulus oocyte complexes (COCs) selected on their morphological characteristics. Three different types of cumulus cell process endings (CCPEs) were identified, one penetrating the cortex, another not penetrating the cortex, and a third form was intermediate and more rare in appearance. The process endings that penetrated the cortex frequently made gap junctions with the oolemma. The division of the three types of CCPEs over the four different COC categories was specific for three of the four categories. The first-category COC predominantly possessed the penetrating CCPE, the fourth-category COC possessed predominantly the nonpenetrating CCPE, and the second and third categories had both types of CCPEs. The metabolic coupling of the cumulus-oocyte contacts was assessed by means of incorporation of 3H-choline into the oocyte. The majority of category 4 COCs transferred low levels of choline into the oocyte while the majority of the oocytes of the other three categories transferred high levels of choline into the oocyte. Category 4 includes a smaller proportion of oocytes capable of cleaving after fertilization than the other three categories. This reduced developmental capacity is probably due to the loss of metabolic coupling before the onset of culture.

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Culture conditions affect meiotic regulation in cumulus cell-enclosed mouse oocytes

Downs

Mastropolo

1997

Mol. Reprod. Dev.

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Maturation of Mammalian Oocytes in Vitro

Cited by 5 publications

References 257 publications

Meiotic Induction in Cumulus Cell-Enclosed Mouse Oocytes: Involvement of the Pentose Phosphate Pathway1

Meiotic Induction in Cumulus Cell-Enclosed Mouse Oocytes: Involvement of the Pentose Phosphate Pathway1

Heterologous cell contacts and metabolic coupling in bovine cumulus oocyte complexes

Culture conditions affect meiotic regulation in cumulus cell-enclosed mouse oocytes

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