In vitro maturation of sheep ovarian oocytes

Szöllősi, Dániel; Desmedt, Véronique; Crozet, Nicole; BRENDER, Corinne; Huneau, D.

doi:10.1051/rnd:19880705

Cited by 20 publications

(13 citation statements)

References 54 publications

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“…In previous experiments of in vitro maturation (IVM) of sheep oocytes, we have shown that, after 6-7 h of culture in the presence of gonadotropins, dispersion of the cumulus and a progressive retraction of FP occurred. The dissociation of the intercellular junctions began concomitantly with germinal vesicle breakdown (GVBD) (Szollosi et al, 1988). Similar observations have been reported by Hyttel et al (1986).…”

Section: Introductionsupporting

confidence: 77%

“…Electron microscopy (EM). COCs were fixed and prepared following the procedure employed and reported previously (Szollosi et al, 1988).…”

Section: Cytological Proceduresmentioning

confidence: 99%

“…After the differentiation of the granulosa and of the cumulus cells (and its innermost cellular layer, the corona radiata), they remain associated with the oocyte by means of foot processes (FP) of the cumulus corona cells that cross the zona pellucida. The bulbous termini of these FP indent deeply the oocyte plasmalemma in sheep (Szollosi et al, 1988) and in cow oocytes (Hyttel et al, 1986). In the contact area, small gap junctions provide electrotonic and ionic communications between the two cell types (Anderson and Albertini, 1976;Gilula, 1977;Szollosi et al, 1978; 0 1991 WILEY-LISS, INC. Larsen et al, 1987).…”

Section: Introductionmentioning

confidence: 99%

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Cytochalasin D treatment induces meiotic resumption in follicular sheep oocytes

Smedt

Szöllősi

1991

Molecular Reproduction Devel

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Ovine cumulus-enclosed oocytes collected from antral follicles (3-5 mm in diameter) were cultured in vitro with 2 x 10(6) granulosa cells/ml in the presence or absence of gonadotropins or in the presence of cytochalasin D (CD). The maturation rate was assessed after 24 h of culture. In the control group, in the presence of gonadotropins (follicle-stimulating hormone-luteinizing hormone (FSH-LH; -10 micrograms/ml) 100% of the oocytes reached metaphase II. Whereas intercellular junctions were no longer present after 6-7 h of culture, germinal vesicle breakdown (GVBD) occurred by the same time. In contrast, in the absence of gonadotropin, the majority of the oocytes (59%) remained blocked in GV stage. The inhibition exerted by the granulosa cells on meiotic resumption was overcome when the cumulus-oocyte complexes (COCs) were incubated in CD (5 micrograms/ml) for 6 h at the beginning of the culture. Under these conditions, 85% of the oocytes matured with extrusion of the first polar body. Cytological analysis by cytofluorescence (NBD phallacidin) and electron microscopy showed that, after 6 h of treatment, CD provoked a redistribution of the microfilaments, mainly in the cumulus cells and to a lesser extent in the oocyte cortex. Intercellular junctions disappeared concomitantly with a significant decrease of the intercellular transport of tritiated uridine. The initiation of GVBD occurred at the same time. These results indicate that the resumption of meiosis was correlated with a loss of both junctional complexes (intermediate and gap junctions) between the cumulus cells and the oocyte.

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Section: Introductionsupporting

confidence: 77%

“…Electron microscopy (EM). COCs were fixed and prepared following the procedure employed and reported previously (Szollosi et al, 1988).…”

Section: Cytological Proceduresmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Cytochalasin D treatment induces meiotic resumption in follicular sheep oocytes

Smedt

Szöllősi

1991

Molecular Reproduction Devel

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“…The occurrence of these events is accompanied by changes in the phosphor- 1 Supported by the Ministero dell'Università e Ricerca Scientifica e Tecnologica (project ex 40%). 2 Correspondence: Sergio Ledda, Department of Animal Biology, University of Sassari, V. Vienna ylation patterns of various cellular proteins [6,7] and structural modification [8,9]. Meiotic progression is regulated by the activity of the maturation-promoting factor (MPF), the universal cell cycle regulator of both mitosis and meiosis.…”

Section: Introductionmentioning

confidence: 99%

Cell Coupling and Maturation-Promoting Factor Activity in In Vitro-Matured Prepubertal and Adult Sheep Oocytes1

Ledda

Bogliolo

Leoni

et al. 2001

Biology of Reproduction

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We examined some differences between prepubertal and adult ovine oocytes; in particular we analyzed the functional status of the cumulus-oocyte complex, protein synthesis during in vitro maturation, and because no information is available on prepubertal and adult sheep, maturation-promoting factor (MPF) fluctuations throughout meiotic progression both in prepubertal and adult sheep oocytes. After 24 h of maturation, percentages of MII oocytes were similar between prepubertal and adult animals. Electron microscopy examinations showed that prepubertal oocytes had fewer transzonal projections than adult oocytes. Methionine uptake was significantly lower in prepubertal cumulus-enclosed oocytes examined through meiotic progression. On the contrary, denuded prepubertal oocytes showed a higher methionine incorporation in the first 4 h of incubation compared with adult oocytes. We also found some differences in MPF activity between prepubertal and adult oocytes at MII stage. In fact, prepubertal MII oocytes had a significantly lower level of MPF activity than adult oocytes did and, after fusion with germinal vesicle oocytes, they were unable to induce nuclear breakdown and chromosome condensation 1-2 h post-fusion, whereas adult MII oocytes could induce these processes. Our findings show that the lesser competence of prepubertal oocytes could be due to morphological anomalies and alterations in physiological activity and that oocytes do not reach full developmental competence until puberty.

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“…This question can be most easily addressed using a physiologically relevant in vitro maturation (IVM) system that allows ovine oocytes and their companion somatic cells to progress through all the biological checkpoints and signalling events required to facilitate oocyte meiotic progression and cumulus mucification and expansion in vivo. Many approaches have been used to support the IVM of oocytes that impact on the mechanism of initiation of oocyte maturation in vitro and the length of time in culture (24-48 h) from a range of species including mouse (De la Fuente et al 1999), cow (Brum et al 2005) and sheep (Szollosi et al 1988). Meiotic progression can occur spontaneously (Hartshorne et al 1994), or be induced by the removal of COCs from the follicle (Leonardsen et al 2000, Nogueira et al 2005 or by the disconnection of oocytes from their cumulus cells (Pincus & Enzmann 1935).…”

Section: Introductionmentioning

confidence: 99%

Characterisation of the cellular and molecular responses of ovine oocytes and their supporting somatic cells to pre-ovulatory levels of LH and FSH during in vitro maturation

2012

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The response of Graafian follicles to pre-ovulatory surge levels of FSH and LH in vivo triggers the terminal differentiation of granulosa cells and oocyte maturation. In polyovular species, the LH-driven signalling uses the epidermal growth factor (EGF)-like ligands AREG, EREG and BTC to promote oocyte maturation and cumulus expansion. This experimental series used a physiologically relevant ovine in vitro maturation (IVM) system to evaluate the impact of exposure to pre-ovulatory levels (100 ng/ml) of LH and FSH on ovine cumulus cell expression of EGF-like ligands in vitro. The serum-free sheep IVM system supported high levels (91.4%) of gonadotrophin-induced maturation of cumulus-enclosed oocytes and embryo development to the blastocyst stage (34.5%). Results were equivalent to a serumbased IVM system (85.1% IVM, 25.8% blastocyst rate; PO0.05) but were significantly different (P!0.05) to serum-free medium without gonadotrophins (69.5% IVM; 8.0% blastocyst rate). Ovine BTC was cloned and sequenced. Gonadotrophin-induced AREG, EREG, BTC and EGFR expressions were quantified in cumulus and mural granulosa cells during IVM. A rapid induction of AREG expression was apparent in both cell types within 30 min of gonadotrophin exposure in vitro. LHCGR (LHR) was detected in mural cells and FSHR in both cumulus and mural granulosa cells. The data confirm the involvement of AREG and EGFR during gonadotrophin-induced cumulus expansion, oocyte maturation and the acquisition of developmental competence by sheep oocytes matured in vitro.

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In vitro maturation of sheep ovarian oocytes

Cited by 20 publications

References 54 publications

Cytochalasin D treatment induces meiotic resumption in follicular sheep oocytes

Cytochalasin D treatment induces meiotic resumption in follicular sheep oocytes

Cell Coupling and Maturation-Promoting Factor Activity in In Vitro-Matured Prepubertal and Adult Sheep Oocytes1

Characterisation of the cellular and molecular responses of ovine oocytes and their supporting somatic cells to pre-ovulatory levels of LH and FSH during in vitro maturation

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