scholarly journals Microarray analysis of mRNA from cumulus cells following in vivo or in vitro maturation of mouse cumulus–oocyte complexes

2013 ◽  
Vol 25 (2) ◽  
pp. 426 ◽  
Author(s):  
Karen L. Kind ◽  
Kelly M. Banwell ◽  
Kathryn M. Gebhardt ◽  
Anne Macpherson ◽  
Ashley Gauld ◽  
...  
Keyword(s):  
Microarray Analysis ◽  
Cell Function ◽  
Cumulus Cell ◽  
Cumulus Cells ◽  
Chorionic Gonadotrophin ◽  
Developmental Competence ◽  
Rt Pcr ◽  
Oocyte Competence

The IVM of mammalian cumulus–oocyte complexes (COCs) yields reduced oocyte developmental competence compared with oocytes matured in vivo. Altered cumulus cell function during IVM is implicated as one cause for this difference. We have conducted a microarray analysis of cumulus cell mRNA following IVM or in vivo maturation (IVV). Mouse COCs were sourced from ovaries of 21-day-old CBAB6F1 mice 46 h after equine chorionic gonadotrophin (5 IU, i.p.) or from oviducts following treatment with 5 IU eCG (61 h) and 5 IU human chorionic gonadotrophin (13 h). IVM was performed in α-Minimal Essential Medium with 50 mIU FSH for 17 h. Three independent RNA samples were assessed using the Affymetrix Gene Chip Mouse Genome 430 2.0 array (Affymetrix, Santa Clara, CA, USA). In total, 1593 genes were differentially expressed, with 811 genes upregulated and 782 genes downregulated in IVM compared with IVV cumulus cells; selected genes were validated by real-time reverse transcription–polymerase chain reaction (RT-PCR). Surprisingly, haemoglobin α (Hba-a1) was highly expressed in IVV relative to IVM cumulus cells, which was verified by both RT-PCR and western blot analysis. Because haemoglobin regulates O2 and/or nitric oxide availability, we postulate that it may contribute to regulation of these gases during the ovulatory period in vivo. These data will provide a useful resource to determine differences in cumulus cell function that are possibly linked to oocyte competence.

scholarly journals Interleukin-6: An Autocrine Regulator of the Mouse Cumulus Cell-Oocyte Complex Expansion Process

Endocrinology ◽  
2009 ◽  
Vol 150 (7) ◽  
pp. 3360-3368 ◽  
Author(s):  
Zhilin Liu ◽  
Daniel G. de Matos ◽  
Heng-Yu Fan ◽  
Masayuki Shimada ◽  
Stephen Palmer ◽  
...  
Keyword(s):  
Immune Responses ◽  
Cell Function ◽  
Cumulus Cell ◽  
Cumulus Cells ◽  
Innate Immune ◽  
Janus Kinase ◽  
Oocyte Competence ◽  
Immune Genes

Ovulation has long been regarded as a process resembling an inflammatory response. Recent studies indicate that genes associated with innate immune responses were also expressed during the ovulation process. Because the innate immune genes are induced in cumulus cell oocyte complexes (COCs) later than the inflammation-associated genes, we hypothesize that COC expansion is dependent on specific sequential changes in cumulus cells. Because IL-6 is a potent mediator of immune responses, we sought to determine what factors regulate the induction of Il6 mRNA in COCs and what impact IL-6 alone would have on COC expansion. We found that the levels of Il6 mRNA increased dramatically during COC expansion, both in vivo and in vitro. Moreover, IL-6, together with its soluble receptor (IL-6SR), could bypass the need for either amphiregulin and/or prostaglandin E2 to induce the expansion of COCs. This ability of IL-6/IL-6SR to induce COC expansion was blocked by the inhibitors to p38MAPK, MAPK kinase 1/2, and Janus kinase. More importantly, when COCs were in vitro maturated in the presence of IL-6, they had a significantly higher embryo transfer rate than the ones without IL-6 and comparable with in vivo matured oocytes. IL-6/IL-6SR activated multiple signaling pathways (Janus kinase/signal transducer and activator of transcription, ERK1/2, p38MAPK, and AKT) and progressively induced genes known to impact COC expansion, genes related to inflammation and immune responses, and some transcription factors. Collectively, these data indicate that IL-6 alone can act as a potent autocrine regulator of ovarian cumulus cell function, COC expansion, and oocyte competence.

scholarly journals Failure to launch: aberrant cumulus gene expression during oocyte in vitro maturation

Reproduction ◽  
2017 ◽  
Vol 153 (3) ◽  
pp. R109-R120 ◽  
Author(s):  
Hannah M Brown ◽  
Kylie R Dunning ◽  
Melanie Sutton-McDowall ◽  
Robert B Gilchrist ◽  
Jeremy G Thompson ◽  
...  
Keyword(s):  
Gene Expression ◽  
Cell Metabolism ◽  
Cumulus Cell ◽  
Cumulus Cells ◽  
Developmental Competence ◽  
Oocyte Competence ◽  
Oocyte Developmental Competence ◽  
Growth Factor Signalling

In vitro maturation (IVM) offers significant benefits for human infertility treatment and animal breeding, but this potential is yet to be fully realised due to reduced oocyte developmental competence in comparison with in vivo matured oocytes. Cumulus cells occupy an essential position in determining oocyte developmental competence. Here we have examined the areas of deficient gene expression, as determined within microarrays primarily from cumulus cells of mouse COCs, but also other species, between in vivo matured and in vitro matured oocytes. By retrospectively analysing the literature, directed by focussing on downregulated genes, we provide an insight as to why the in vitro cumulus cells fail to support full oocyte potential and dissect molecular pathways that have important roles in oocyte competence. We conclude that the roles of epidermal growth factor signalling, the expanded extracellular matrix, cumulus cell metabolism and the immune system are critical deficiencies in cumulus cells of IVM COCs.

scholarly journals Role for cumulus cell-produced EGF-like ligands during primate oocyte maturation in vitro

2009 ◽  
Vol 296 (5) ◽  
pp. E1049-E1058 ◽  
Author(s):  
Jenna K. Nyholt de Prada ◽  
Young S. Lee ◽  
Keith E. Latham ◽  
Charles L. Chaffin ◽  
Catherine A. VandeVoort
Keyword(s):  
Rhesus Macaque ◽  
Oocyte Maturation ◽  
Egf Receptor ◽  
Cumulus Cell ◽  
Cumulus Cells ◽  
Developmental Competence ◽  
Lower Percentage ◽  
Egfr Activation

The developmental competence of in vitro-matured (IVM) rhesus macaque cumulus oocyte complexes (COCs) is deficient compared with in vivo-matured (IVM) oocytes. To improve oocyte quality and subsequent embryo development following IVM, culture conditions must be optimized. A series of experiments was undertaken to determine the role of epidermal growth factor (EGF) during IVM of rhesus macaque COCs. The addition of Tyrphostin AG-1478 (a selective inhibitor of the EGF receptor EGFR) to the IVM medium yielded fewer oocytes maturing to metaphase II of meiosis II (MII), decreased cumulus expansion, and a lower percentage of embryos that developed to the blastocyst stage compared with untreated IVM controls, indicating that EGFR activation is important for IVM maturation in the rhesus macaque. However, the addition of recombinant human EGF (r-hEGF) to the IVM medium did not enhance outcome. The expression of mRNAs encoding the EGF-like factors amphiregulin, epiregulin, and betacellulin in cumulus cells indicates that these factors produced by cumulus cells may be responsible for maximal EGFR activation during oocyte maturation, precluding any further effect of exogenous r-hEGF. Additionally, these results illustrate the potential futility of exogenous supplementation of IVM medium without prior knowledge of pathway activity.

P–219 mtDNA content in bovine cumulus cells does not predict oocytés developmental competence

2021 ◽  
Vol 36 (Supplement_1) ◽  
Author(s):  
Á Martíne. Moro ◽  
I Lamas-Toranzo ◽  
L González-Brusi ◽  
A Pérez-Gómez ◽  
P Bermejo-Álvarez
Keyword(s):  
Cumulus Cell ◽  
Cumulus Cells ◽  
Oocyte Quality ◽  
Blastocyst Stage ◽  
Early Embryo ◽  
Developmental Competence ◽  
Success Rates ◽  
Developmental Potential ◽  
Mtdna Sequence

Abstract Study question Does cumulus cell mtDNA content correlate with oocyte developmental potential in the bovine model? Summary answer The relative amount of mtDNA content did not vary significantly in oocytes showing different developmental outcomes following IVF What is known already Cumulus cells are closely connected to the oocyte through transzonal projections, serving essential metabolic functions during folliculogenesis. These oocyte-supporting cells are removed and discarded prior to ICSI, thereby constituting an interesting biological material on which to perform molecular analysis aimed to predict oocyte developmental competence. Previous studies have positively associated oocytés mtDNA content with developmental potential in both animal models and women. However, it remains debatable whether mtDNA content in cumulus cells could be used as a proxy to infer oocyte developmental potential. Study design, size, duration Bovine cumulus cells were allocated into three groups according to the developmental potential of the oocyte: 1) oocytes developing to blastocysts following IVF (Bl+Cl+), 2) oocytes cleaving following IVF but arresting their development prior to the blastocyst stage (Bl-Cl+), and 3) oocytes not cleaving following IVF (Bl-Cl-). Relative mtDNA content was analysed in 40 samples/group, each composed by the cumulus cells from one cumulus-oocyte complex (COC). Participants/materials, setting, methods Bovine cumulus-oocyte complexes were obtained from slaughtered cattle and individually matured in vitro (IVM). Following IVM, cumulus cells were removed by hyaluronidase treatment, pelleted, snap frozen in liquid nitrogen and stored at –80 ºC until analysis. Cumulus-free oocytes were fertilized and cultured in vitro individually and development was recorded for each oocyte. Relative mtDNA abundance was determined by qPCR, amplifying a mtDNA sequence (COX1) and a chromosomal sequence (PPIA). Statistical differences were tested by ANOVA. Main results and the role of chance Relative mtDNA abundance did not differ significantly (ANOVA p > 0.05) between the three groups exhibiting different developmental potential (1±0.06 vs. 1.19±0.05 vs. 1.11±0.05, for Bl+Cl+ vs. Bl-Cl+ vs. Bl-Cl-, mean±s.e.m.). Limitations, reasons for caution Experiments were conducted in the bovine model. Although bovine folliculogenesis, monoovulatory ovulation and early embryo development exhibit considerable similarities with that of humans, caution should be taken when extrapolating these data to humans. Wider implications of the findings: The use of molecular markers for oocyte developmental potential in cumulus cells could be used to enhance success rates following single-embryo transfer. Unfortunately, mtDNA in cumulus cells was not found to be a good proxy for oocyte quality. Trial registration number Not applicable

scholarly journals α-Tocopherol modifies the expression of genes related to oxidative stress and apoptosis during in vitro maturation and enhances the developmental competence of rabbit oocytes

2018 ◽  
Vol 30 (12) ◽  
pp. 1728 ◽  
Author(s):  
M. Arias-Álvarez ◽  
R. M. García-García ◽  
J. López-Tello ◽  
P. G. Rebollar ◽  
A. Gutiérrez-Adán ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Cell Cycle ◽  
In Vitro Maturation ◽  
Cumulus Cell ◽  
Rabbit Model ◽  
Developmental Competence ◽  
Antioxidant Agents ◽  
Junction Protein

The developmental competence of in vitro maturation (IVM) oocytes can be enhanced by antioxidant agents. The present study investigated, for the first time in the rabbit model, the effect of adding α-tocopherol (0, 100, 200 and 400 µM) during IVM on putative transcripts involved in antioxidant defence (superoxide dismutase 2, mitochondrial (SOD2), glutathione peroxidase 1 (GPX1), catalase (CAT)), cell cycle regulation and apoptosis cascade (apoptosis tumour protein 53 (TP53), caspase 3, apoptosis-related cysteine protease (CASP3)), cell cycle progression (cellular cycle V-Akt murine thymoma viral oncogene homologue 1 (AKT1)), cumulus expansion (gap junction protein, alpha 1, 43 kDa (GJA1) and prostaglandin-endoperoxide synthase 2 (prostaglandin G/H synthase and cyclo-oxygenase) (PTGS2)) and metabolism (glucose-6-phosphate dehydrogenase (G6PD)). Meiotic progression, mitochondrial reallocation, cumulus cell apoptosis and the developmental competence of oocytes after IVF were also assessed. Expression of SOD2, CAT, TP53, CASP3 and GJA1 was downregulated in cumulus–oocyte complexes (COCs) after IVM with 100 μM α-tocopherol compared with the group without the antioxidant. The apoptotic rate and the percentage of a non-migrated mitochondrial pattern were lower in COCs cultured with 100 μM α-tocopherol, consistent with better-quality oocytes. In fact, early embryo development was improved when 100 μM α-tocopherol was included in the IVM medium, but remained low compared with in vivo-matured oocytes. In conclusion, the addition of 100 μM α-tocopherol to the maturation medium is a suitable approach to manage oxidative stress and apoptosis, as well as for increasing the in vitro developmental competence of rabbit oocytes.

195 ALTERED mRNA TRANSCRIPT EXPRESSION OF IN VITRO- VERSUS IN VIVO-MATURED PORCINE OOCYTES

2012 ◽  
Vol 24 (1) ◽  
pp. 210
Author(s):  
L. D. Spate ◽  
B. K. Redel ◽  
K. M. Whitworth ◽  
W. G. Spollen ◽  
S. M. Blake ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Real Time ◽  
Real Time Pcr ◽  
Genetic Background ◽  
Cumulus Cells ◽  
Developmental Competence ◽  
Illumina Genome Analyzer ◽  
Similar Genetic Background

In contrast to oocytes matured in vitro, porcine embryos that result from in vivo maturation and fertilization have a high developmental competence and readily make the transition from oocyte to blastocyst. This observation led us to investigate the transcript profile differences between in vivo- and in vitro-matured porcine oocytes. For the in vivo-matured group, oviducts of 3 gilts of similar genetic background were flushed 2 days after detection of standing oestrus. MII oocytes were collected in pools of 10 and snap frozen in liquid nitrogen for RNA isolation. The in vitro-matured oocytes were obtained by euthanizing 3 gilts, again with a similar genetic background and recovering the ovaries. Follicles (2 to 8 mm in size) were aspirated and oocytes with multiple layers of cumulus cells and uniform cytoplasm were placed in M-199 supplemented with LH, FSH and epidermal growth factor for 42 h. Upon maturation, cumulus cells were stripped and the healthy MII oocytes were collected in pools of 10 and snap frozen. Total RNA was extracted from 3 pools of 10 oocytes for both treatments using an All prep DNA/RNA micro isolation kit (Qiagen, Valencia, CA, USA). Complementary DNA was synthesized using oligo (dT′) primed reverse transcriptase with superscript III (Invitrogen, Carlsbad, CA, USA). Second-strand cDNA was synthesized using DNA polymerase I and sequenced using Illumina Genome Analyzer II. All reads were aligned to a custom-built porcine transcriptome. There were over 18 million reads in the 2 maturation groups that tiled to the 34 433-member transcriptome: 1317 transcripts were detected with a P ≤ 0.1 (Students t-test), a minimum of 7 reads in at least 1 of the treatments and ≥2-fold difference. Real-time PCR was used on selected transcripts. Comparative CT Method was used on an IQ real-time PCR system with the Bio–Rad SYBR green mix. Statistical differences were determined using the Proc general linear model procedure of SAS (SAS Institute Inc., Cary, NC) and means separated with a l.s.d. (P ≤ 0.05). The misrepresented transcripts from the sequencing data were also characterized using the functional annotation tool DAVID. Twelve pathways were overrepresented in the in vitro-matured oocytes (the top 4 are pathways to cancer, spliceosome, cell cycle and ubiquitin-mediated proteolysis). Eight pathways were underrepresented in the in vitro-matured oocytes (the top 4 are cytoskeleton regulation, T-cell receptor signaling pathway, ubiquitin-mediated proteolysis and cell cycle). Eight transcripts were selected for real-time PCR. ZP2 was higher in the in vitro-matured oocytes as determined by both sequencing and real time. ATG4, HSP90, UBAP2 and SOX4 were not different, regardless of assay. SLC7A3, MRPS36 and PDHX2 were not different based on sequencing, but based on real-time MRPS36 and PDHX2, were higher in the in vivo group and SLC7A3 was higher in the in vitro group. In conclusion, there is an abundance of misregulated transcripts and altered pathways in in vitro-matured oocytes. This dataset is a tool that may provide clues to improve the in vitro maturation process so that in vitro-matured oocytes will be more like their in vivo-matured counterparts, thus improving developmental competence. Funded by Food for the 21st Century.

79 microRNA EXPRESSION IN BOVINE CUMULUS CELLS

2015 ◽  
Vol 27 (1) ◽  
pp. 133
Author(s):  
K. Uhde ◽  
L. T. A. van Tol ◽  
T. A. E. Stout ◽  
B. A. J. Roelen
Keyword(s):  
Mirna Expression ◽  
Reference Genes ◽  
Noncoding Rna ◽  
Ovarian Follicle ◽  
Cumulus Cell ◽  
Cumulus Cells ◽  
Developmental Competence ◽  
Small Samples ◽  
Variable Expression

A mammalian oocyte within an ovarian follicle is surrounded by cumulus cells, together this structure is known as the cumulus-oocyte complex (COC). Cumulus cells are important for the development of the oocyte, they support the maturation process of the oocyte within the ovary and aid in sperm recognition. Because it is known that a Dicer knockout leads to infertility, microRNAs (miRNA) are focused to have an important role in oocyte development. MiRNAs are small noncoding RNA sequences that act as transcriptional regulators. Little is known about the expression of miRNA in cumulus cells or how cumulus-derived miRNA may regulate or be used to indicate the developmental competence of the maturing oocyte. Our aim was to investigate miRNA expression in oocytes and to identify and establish how specific miRNA influence the acquisition of developmental competence by bovine oocytes. Normalization of qPCR data requires stable reference genes. To this end, we tested the expression of various miRNA with respect to their ability to be used as reference miRNA for bovine cumulus cells; these included miR-103, miR-93, miR-26, let-7a, miR-191, and the small noncoding nuclear RNA U6. Cumulus-oocyte complexes were recovered from the ovaries of slaughtered cows and matured in vitro. Small samples of cumulus cells were collected from these COC before and after maturation. From the cumulus cell groups recovered at different stages, small RNA were extracted and cDNA was synthesised, followed by qRT-PCR. To identify the optimal combination of reference genes, the geNorm algorithm was used. MiR-26a and let-7a were identified as the most stably expressed miRNAs, whereas U6 showed the most variable expression levels. Future investigations are planned to identify miRNA in cumulus cells that can be used as markers for oocyte developmental competence. Using a single oocyte-embryo culture system will enable us to retrospectively relate cumulus miRNA expression to the developmental capacity of the oocyte.This work was supported by EU FP7 EpiHealthNet (N°317146).

205 CUMULUS CELL MORPHOLOGY BEFORE AND AFTER IN VITRO MATURATION AS AN INDICATOR OF PORCINE OOCYTE DEVELOPMENTAL COMPETENCE

2010 ◽  
Vol 22 (1) ◽  
pp. 260
Author(s):  
M. Bertoldo ◽  
P. K. Holyoake ◽  
G. Evans ◽  
C. G. Grupen
Keyword(s):  
Cell Morphology ◽  
In Vitro Maturation ◽  
Cumulus Cell ◽  
Cumulus Cells ◽  
Oocyte Quality ◽  
Developmental Competence ◽  
Oocyte Developmental Competence ◽  
Before And After ◽  
Follicle Size

Effective in vitro maturation (IVM) is essential for successful in vitro embryo production. The morphology of the cumulus investment before and after IVM may be a useful noninvasive indicator of oocyte quality. In pigs, oocyte developmental competence is reduced during the summer months. The aim of this study was to determine whether the morphology of cumulus-oocyte complexes (COC) before and after IVM are associated with oocyte quality, using COC collected from small and large follicles in summer and winter as models of poor and good oocyte quality. Ovaries were collected from sows slaughtered 4 days after weaning. The COC recovered from small (3-4 mm) and large (5-8 mm) antral follicles were morphologically graded and parthenogenetically activated following IVM during winter (n = 1419; 10 replicates) and summer (n = 2803; 10 replicates). Grade 1 and 2 COC had >2 layers of compact cumulus cells and a homogenous cytoplasm. Grade 3 COC were either partially or fully denuded, had a heterogeneous cytoplasm, or were vacuolated or dark in color. Grade 4 COC had expanded cumulus cells. Cumulus expansion was also assessed subsequent to IVM. The COC recorded as having a cumulus expansion index (CEI) of 1 had the poorest expansion with no detectable response to IVM, whereas those with a CEI of 4 had the greatest amount of expansion, including that of the corona radiata. Data were analyzed using a generalized linear mixed model in GenStat® (release 10, VSN International, Hemel Hempstead, UK). There was an effect of follicle size for Grade 1 COC, with COC from large follicles in both seasons yielding better quality COC (P < 0.05). The proportion of COC in Grade 2 was higher in small follicles during winter compared with large follicles, but there were no differences between follicle sizes during summer (P < 0.05). The proportion of COC with CEI 1 was highest in COC from small follicles during summer (P < 0.05). The proportion of COC from large follicles with CEI 2 was higher during summer compared with winter (P < 0.05). There were no seasonal or follicle size effects on COC with CEI 3 or 4 (P > 0.05). The proportion of oocytes that developed to blastocysts was greater in winter than in summer (39.06% ± 5.67 v. 22.27% ± 4.01; P < 0.05). Oocytes derived from large follicles had a greater ability to form blastocysts compared with those from small follicles (37.13% ± 5.65 v. 23.32% ± 4.56; P < 0.06). Morphological assessment of cumulus cells before and after IVM may be a useful tool to evaluate the effects of follicle size on oocyte developmental competence. However, the results of the present study indicate that cumulus cell morphology is not a good indicator of the effect of season on oocyte developmental competence.

168 INHIBITION OF BOVINE OOCYTE CUMULUS CELL PROGESTERONE SYNTHESIS DURING IN VITRO MATURATION AFFECTS CHROMOSOME ALIGNMENT AND SPINDLE INTEGRITY IN FERTILIZED EGGS AND EARLY EMBRYOS

2014 ◽  
Vol 26 (1) ◽  
pp. 198
Author(s):  
E. Daly ◽  
A. G. Fahey ◽  
M. M. Herlihy ◽  
T. Fair
Keyword(s):  
Embryo Development ◽  
Cumulus Cell ◽  
Cumulus Cells ◽  
Early Embryo ◽  
Developmental Competence ◽  
Bovine Oocyte ◽  
Spindle Formation ◽  
Vitro Fertilization ◽  
Time Treatment

We have previously demonstrated the importance of progesterone (P4) synthesis by cumulus cells during oocyte maturation in vitro (IVM) for bovine oocyte acquisition of developmental competence and subsequent embryo development (Aparicio et al. 2011 Biol. Reprod. 84). The aim of this study was to identify key processes that may be deregulated by the inhibition of P4 signalling in the cumulus–oocyte complex (COC) during IVM. To this end, good quality immature COC were placed in IVM medium [TCM-199 supplemented with 10% (vol/vol) FCS and 10 ng mL–1 epidermal growth factor] and cultured at 39°C for 22 h in a humidified atmosphere containing 5% CO2, in the presence or absence of 10 μM trilostane (which blocks P4 synthesis by inhibiting 3 β-hydroxysteroid dehydrogenase; Stegram Pharmaceuticals Ltd., Surrey, UK). Matured COC were washed and placed in 250 μL of fertilization medium (25 mM bicarbonate, 22 mM Na-lactate, 1 mM Na-pyruvate, 6 mg mL–1 fatty acid-free BSA, and 10 mg mL–1 heparin). In vitro fertilization (IVF) was performed with 250 μL of frozen–thawed semen at a final concentration of 1 × 106 spermatozoa mL–1 at 39°C under 5% CO2 during 20 h. Presumptive zygotes were denuded, washed, and transferred to 25-μL culture droplets (SOF + 5% FCS) at 39°C under 5% CO2, 90% of N2, and 5% O2 atmosphere with maximum humidity. Subsets of presumptive fertilized eggs and developing embryos were recovered at 6, 72, 120, and 192 h postinsemination (hpi) and processed for confocal whole-mount immunocytochemistry. The meiotic and mitotic spindles and chromosomes were visualised by immunofluorescent labelling of α-tubulin and 4′,6-diamindino-2-phenylindole (DAPI), respectively, and classified as normal if the chromosomes were correctly aligned or appropriately segregated, or abnormal if lagging chromosomes or abnormal chromosome segregation were observed. Samples were collected from 5 replicates (n = 50 zygotes/embryos per treatment, per timepoint) and a total of 157 spindles were observed. Logistic regression analysis was conducted to determine the probability of abnormal spindle formation. The incidence of spindle abnormality was regressed on time, treatment, and treatment by time. For all time points, there was significant reduction in the odds of abnormal spindle formation in control samples versus trilostane-treated samples (P < 0.001). In conclusion, our data imply a role for P4 signalling in maintaining spindle integrity during oocyte meiotic maturation and progression through the initial mitotic divisions of early embryo development in cattle.

159 EFFECT OF 3-ISOBUTYL-1-METHYLXANTHINE (IBMX) ON THE GERMINAL VESICLE STAGE OF PORCINE OOCYTES DURING OOCYTE COLLECTION IN VITRO

2014 ◽  
Vol 26 (1) ◽  
pp. 193
Author(s):  
R. Appeltant ◽  
J. Beek ◽  
D. Maes ◽  
A. Van Soom
Keyword(s):  
Germinal Vesicle ◽  
Cyclic Adenosine Monophosphate ◽  
Adenosine Monophosphate ◽  
Cumulus Cells ◽  
Guanosine Monophosphate ◽  
Developmental Competence ◽  
Meiotic Arrest ◽  
Oocyte Collection

When using modern maturation conditions for in vitro maturation, pig oocytes yield ~20% blastocysts only. One problem is that cumulus cells, which are normally connected with the immature oocyte by cellular projections penetrating through the zona pellucida and with the oolemma via gap junctions, are prematurely losing these connections after the cumulus–oocyte complex is removed from the follicle. The oocyte possesses a type 3 phosphodiesterase, which degrades 3′,5′-cyclic adenosine monophosphate (cAMP), and this activity is inhibited by supply of 3′,5′-cyclic guanosine monophosphate (cGMP) to the oocyte via the cumulus cells. Consequently, cAMP levels, which are typically high during early stages of oocyte maturation in vivo, decrease, leading to spontaneous nuclear maturation and oocytes of low developmental competence. Therefore, the maintenance of these cumulus-oocyte connections is important to keep cAMP high and the oocyte under meiotic arrest. One way to prevent this drop in cAMP is using N6, 2′-o-dibutyryladenosine 3′,5′-cyclic monophosphate sodium (dbcAMP) that causes an arrest at germinal vesicle (GV) stage II (Funahashi et al. 1997 Biol. Reprod. 57, 49–53). Another option is collecting the oocytes in a medium containing the phoshodiesterase inhibitor, IBMX. The present study investigated the influence of IBMX on the progression of the GV of the oocyte after collection, just before the start of the maturation procedure. The GV stage was defined according to Sun et al. (2004 Mol. Reprod. Dev. 69, 228–234). In parallel with the findings on dbcAMP, we hypothesised an arrest at GV II by the presence of IBMX during collection. One group of oocytes were collected in HEPES-buffered TALP without IBMX (n = 375) and another group in the same medium containing 0.5 mM IBMX (n = 586). An average incubation time of 140 min was applied in both groups, and 3 replicates were performed. The proportions of oocytes before or at GV II and beyond GV II were compared in both groups using logistic regression analysis. The proportion of oocytes was included as dependent variable and group (IBMX addition or not) as independent variable. Replicate was also included in the model. The proportion of oocytes before or at GV II was not statistically significant between the group without and the group with IBMX (59.2 v. 58.7% respectively; P > 0.05). In conclusion, the use of IBMX during oocyte collection did not influence the state of the germinal vesicle of the oocyte during collection, indicating that IBMX did not cause a meiotic arrest in the oocytes during collecting in vitro.

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