210 DNA METHYLATION AND HYDROXYMETHYLATION ANALYSIS IN A MODEL OF OOCYTE DIFFERENTIAL DEVELOPMENTAL COMPETENCE IN SHEEP

2015 ◽  
Vol 27 (1) ◽  
pp. 195
Author(s):  
L. Masala ◽  
D. Bebbere ◽  
G. P. Burrai ◽  
F. Ariu ◽  
L. Bogliolo ◽  
...  
Keyword(s):  
Dna Methylation ◽  
Embryo Development ◽  
Oocyte Quality ◽  
Developmental Competence ◽  
Ctcf Binding ◽  
Ctcf Binding Site ◽  
Global Methylation ◽  
Tet Genes ◽  
Lower Expression

DNA methylation is an important epigenetic mark that plays a role in gene regulation by the addition of a methyl group to CpG islands in the DNA. Despite being relatively stable in somatic cells, DNA methylation is subject to reprogramming during embryo development and gametogenesis. The aim of this work was to evaluate different aspects of DNA methylation in relation to oocyte quality in the ovine species. A model of differential developmental competence consisting in ovine oocytes and in vitro produced (IVP) blastocysts derived from adult (AD) and prepubertal (PR) donors, was used. The methylation was analysed in terms of: expression of a panel of genes involved in DNA methylation [DNA methyltransferases (DNMTs)] and demethylation [ten-eleven translocation dioxygenases (TET)] in oocytes and blastocysts; global methylation and hydroxymethylation by direct immunofluorescence; locus-specific methylation of 2 imprinted genes by pyrosequencing. Gene relative quantification was performed by RNA reverse transcription followed by real-time PCR. Pools of 10 immature (GV) and in vitro-matured (MII) oocytes and (IVP) blastocysts derived from AD and PR donors (4 replicates per class) were analysed. Lower expression of TET1, TET2, and TET3 was observed in PR GV oocytes (ANOVA; P < 0.05), while no significant differences were found for the enzymes involved in methylation (DNMT1, DNMT3A, DNMT3B; ANOVA; P > 0.05). The levels of all the genes studied showed no significant differences in embryos at blastocyst stage (ANOVA; P > 0.05). Methylation and hydroxymethylation immunostaining were performed in GV and MII oocytes using anti-5-methylcytosine mouse mAb and 5-hydroxymethylcytosine rabbit pAB. High levels of DNA methylation were observed in both AD and PR GV and MII oocytes, while hydroxymethylation immunopositivity was scattered evident throughout the gamete chromatin. Pyrosequencing of bisulfite converted DNA was used to determine the methylation status within differentially methylated regions (DMR) of maternally imprinted H19 (CTCF binding site IV; 11 CpG sites) and paternally imprinted IGF2R (17CpG sites within intron 2). No differences were observed between classes of oocytes for each gene (pools of 40 oocytes per replicate, 3 replicates per class; ANOVA; P > 0.05). Our work shows no differences in the expression of the enzymes involved in methylation, in accordance with the results of global and locus specific methylation analysis. Conversely, we observed lower expression of the TET genes in PR GV oocytes (ANOVA; P > 0.05). TET1, TET2, and TET3, whose expression has never been studied in ovine, generate 5-hydroxymethlcytosine (5hmC) by oxidation of 5-methylcytosine (5mC), and are involved in active DNA demethylation during early embryo development. Our observation of lower expression of the TET genes in lower competence PR GV oocytes suggests that epigenetic mechanisms may affect oocyte quality and paves the way to better understand methylation dynamics during sheep pre-implantation development.

scholarly journals DNA damage in cumulus cells generated after the vitrification of in vitro matured porcine oocytes and its impact on fertilization and embryo development

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Alma López ◽  
Miguel Betancourt ◽  
Yvonne Ducolomb ◽  
Juan José Rodríguez ◽  
Eduardo Casas ◽  
...  
Keyword(s):  
Dna Damage ◽  
Embryo Development ◽  
Tail Length ◽  
Cumulus Cells ◽  
Cell Types ◽  
Oocyte Quality ◽  
Blastocyst Stage ◽  
Developmental Competence ◽  
Development Rates

Abstract Background The evaluation of the DNA damage generated in cumulus cells after mature cumulus-oocyte complexes vitrification can be considered as an indicator of oocyte quality since these cells play important roles in oocyte developmental competence. Therefore, the aim of this study was to determine if matured cumulus-oocyte complexes exposure to cryoprotectants (CPAs) or vitrification affects oocytes and cumulus cells viability, but also if DNA damage is generated in cumulus cells, affecting fertilization and embryo development. Results The DNA damage in cumulus cells was measured using the alkaline comet assay and expressed as Comet Tail Length (CTL) and Olive Tail Moment (OTM). Results demonstrate that oocyte exposure to CPAs or vitrification reduced oocyte (75.5 ± 3.69%, Toxicity; 66.7 ± 4.57%, Vitrification) and cumulus cells viability (32.7 ± 5.85%, Toxicity; 7.7 ± 2.21%, Vitrification) compared to control (95.5 ± 4.04%, oocytes; 89 ± 4.24%, cumulus cells). Also, significantly higher DNA damage expressed as OTM was generated in the cumulus cells after exposure to CPAs and vitrification (39 ± 17.41, 33.6 ± 16.69, respectively) compared to control (7.4 ± 4.22). In addition, fertilization and embryo development rates also decreased after exposure to CPAs (35.3 ± 16.65%, 22.6 ± 3.05%, respectively) and vitrification (32.3 ± 9.29%, 20 ± 1%, respectively). It was also found that fertilization and embryo development rates in granulose-intact oocytes were significantly higher compared to denuded oocytes in the control groups. However, a decline in embryo development to the blastocyst stage was observed after CPAs exposure (1.66 ± 0.57%) or vitrification (2 ± 1%) compared to control (22.3 ± 2.51%). This could be attributed to the reduction in both cell types viability, and the generation of DNA damage in the cumulus cells. Conclusion This study demonstrates that oocyte exposure to CPAs or vitrification reduced viability in oocytes and cumulus cells, and generated DNA damage in the cumulus cells, affecting fertilization and embryo development rates. These findings will allow to understand some of the mechanisms of oocyte damage after vitrification that compromise their developmental capacity, as well as the search for new vitrification strategies to increase fertilization and embryo development rates by preserving the integrity of the cumulus cells.

170 INFLUENCE OF OOCYTE QUALITY AND DIFFERENT MEDIA SUPPLEMENT ON IN VITRO MATURATION, CLEAVAGE, AND EMBRYO DEVELOPMENT OF BUFFALO (BUBALUS BUBALIS) OOCYTES

2014 ◽  
Vol 26 (1) ◽  
pp. 199
Author(s):  
M. M. Waheed ◽  
K. H. El-Shahat ◽  
A. M. Hammam
Keyword(s):  
Embryo Development ◽  
In Vitro Maturation ◽  
Cumulus Cell ◽  
Oocyte Quality ◽  
Bubalus Bubalis ◽  
Poor Quality ◽  
Developmental Competence ◽  
Control Group ◽  
Excellent Quality

A series of 4 factorial-arranged experiments were conducted to study the effect of oocyte quality and different in vitro maturation (IVM) media supplements on IVM, cleavage, and embryo development of buffalo (Bubalus bubalis) oocytes. Buffalo ovaries were collected at a local abattoir in a warm (32–35°C) saline (0.9% NaCl), and oocytes were aspirated using an 18-gauge needle. In experiment 1, oocytes (n = 320) were classified according to the number of cumulus cell layers and morphology of ooplasm as excellent, good, or fair. Oocytes were cultured for IVM, fertilization, and embryo culture (IVMFC) in TCM-199 + 10% FCS. In experiment 2, excellent quality oocytes (n = 237) were subjected to IVM in TCM-199 enriched with either 10% FCS or oestrous buffalo serum (EBS; 20–40 pg mL–1) and then fertilized using frozen–thawed buffalo semen capacitated in Bracket and Oliphant's (BO) medium containing heparin (0.02 mg mL–1) and sodium caffeine benzoate (3.89 mg mL–1). In experiment 3, oocytes (n = 290) were classified into 2 groups; Group 1, without gonadotropins, served as a control; Group 2, in which IVM medium was supplemented with 20 IU mL–1 equine chorionic gonadotropins (eCG). Experiment 4 was carried out to examine the suitable capacitating agent added to BO medium, either heparin or caffeine or both (n = 210 fertilized oocytes). In all experiments (multiple replicates), oocytes (2–6 mm in diameter) were kept at 39°C under 5% CO2 for IVMFC and examined several times for cleavage and embryo development (morula and blastocyst). Statistical analysis was carried out using Chi-squared test. Excellent and good quality oocytes produced a higher (P < 0.05) maturation, cleavage, and morula development rates than poor quality oocytes (70% and 65% v. 33.3%), (50% and 46.2% v. 25%), and (42.9% and 33.3% v. 10%), respectively. Blastocyst production rate was also higher (P < 0.05) for excellent compared with good quality oocytes (28.6% v. 16.7%, respectively). In experiment 2, the IVM and cleavage rates were significantly higher (P < 0.05) in IVM medium plus 10% EBS than those cultured in 10% FCS (73% v. 45% and 50% v. 33.3%, respectively). In experiment 3, the addition of eCG to maturation medium increased (P < 0.05) developmental competence of buffalo oocytes (IVMFC) compared with control medium (16% v. 4%). In experiment 4, the addition of heparin together with caffeine to BO medium produced significantly higher (P < 0.05) cleavage and embryo developmental rates compared with heparin or caffeine alone (56.3% v. 33.3% and 35.7%, respectively; 22.2% v. 10% and 8%, respectively). In conclusion, excellent quality oocytes cultured in IVM medium supplemented with either EBS or eCG and fertilized with capacitated buffalo spermatozoa in BO medium enriched with heparin and caffeine progressively enhanced developmental competence of buffalo oocytes.

scholarly journals Effects of different oocyte retrieval and in vitro maturation systems on bovine embryo development and quality

Zygote ◽  
2014 ◽  
Vol 23 (3) ◽  
pp. 367-377 ◽  
Author(s):  
Sandra Milena Bernal ◽  
Julia Heinzmann ◽  
Doris Herrmann ◽  
Bernd Timmermann ◽  
Ulrich Baulain ◽  
...  
Keyword(s):  
Gene Expression ◽  
Embryo Development ◽  
Expression Profiles ◽  
Expression Patterns ◽  
Developmental Competence ◽  
Bovine Embryo ◽  
Global Methylation ◽  
Oocyte Developmental Competence

SummaryCyclic adenosine monophosphate (cAMP) modulators have been used to avoid spontaneous oocyte maturation and concomitantly improve oocyte developmental competence. The current work evaluated the effects of the addition of cAMP modulators forskolin, 3-isobutyl-1-methylxanthine (IBMX) and cilostamide during in vitro maturation on the quality and yields of blastocysts. The following experimental groups were evaluated: (i) slicing or (ii) aspiration and maturation in tissue culture medium (TCM)199 for 24 h (TCM24slicing and TCM24aspiration, respectively), (iii) aspiration and maturation in the presence of cAMP modulators for 30 h (cAMP30aspiration) and in vivo-produced blastocysts. In vitro-matured oocytes were fertilized and presumptive zygotes were cultured in vitro to assess embryo development. Cleavage, blastocyst formation, blastocyst cell number, mRNA abundance of selected genes and global methylation profiles were evaluated. Blastocyst rate/zygotes for the TCM24aspiration protocol was improved (32.2 ± 2.1%) compared with TCM24slicing and cAMP30aspiration (23.4 ± 1.2% and 23.3 ± 2.0%, respectively, P<0.05). No statistical differences were found for blastocyst cell numbers. The mRNA expression for the EGR1 gene was down-regulated eight-fold in blastocysts that had been produced in vitro compared with their in vivo counterparts. Gene expression profiles for IGF2R, SLC2A8, COX2, DNMT3B and PCK2 did not differ among experimental groups. Bovine testis satellite I and Bos taurus alpha satellite methylation profiles from cAMP30aspiration protocol-derived blastocysts were similar to patterns that were observed in their in vivo equivalents (P > 0.05), while those from the other groups were significantly elevated. It is concluded that retrieval, collection systems and addition of cAMP modulators can affect oocyte developmental competence, which is reflected not only in blastocyst rates but also in global DNA methylation and gene expression patterns.

The Role of Oocyte Quality in Explaining “Unexplained” Infertility

2020 ◽  
Vol 38 (01) ◽  
pp. 021-028
Author(s):  
Hayden Anthony Homer
Keyword(s):  
Embryo Development ◽  
Natural Aging ◽  
Building Blocks ◽  
Oocyte Quality ◽  
Developmental Competence ◽  
Semen Parameters ◽  
Serum Progesterone ◽  
Vitro Fertilization ◽  
Preimplantation Embryo Development

AbstractInfertility is described as unexplained when pregnancy does not occur despite ovulation, patent Fallopian tubes, and normal semen parameters. Oocyte developmental competence (or quality) is rate-limiting for pregnancy success as oocytes provide virtually all the cellular building blocks including mitochondria required during embryogenesis. However, available tests estimate oocyte numbers (anti-Müllerian hormone, follicle-stimulating hormone and antral follicle count) and ovulation (luteal phase serum progesterone) but not the third, and most pivotal, oocyte-specific parameter, quality. Severe depletion of the follicular reserve manifests as premature ovarian insufficiency and is an obvious cause of anovulation with overt symptoms and clear diagnostic criteria. In contrast, there are no biomarkers of poor oocyte quality other than through in vitro fertilization when readouts of oocyte quality such as preimplantation embryo development can be assessed. The most common cause of poor oocyte quality is natural aging, which is strongly tied to reduced oocyte mitochondrial efficiency and increased oxidative stress. In younger women, quality may also be impaired due to accelerated aging or sporadic genetic mutations which cause severe defects during oocyte and embryo development. Thus, poor oocyte quality often provides an explanation for infertility, but because it cannot be measured using conventional tests, many cases of infertility are often incorrectly labeled “unexplained.” Since female age remains the best predictor of oocyte quality, age over 37 years should be considered an independent diagnostic criterion.

Differential effects of high and low glucose concentrations during lipolysis-like conditions on bovine in vitro oocyte quality, metabolism and subsequent embryo development

2017 ◽  
Vol 29 (11) ◽  
pp. 2284 ◽  
Author(s):  
J. De Bie ◽  
W. F. A. Marei ◽  
V. Maillo ◽  
L. Jordaens ◽  
A. Gutierrez-Adan ◽  
...  
Keyword(s):  
Embryo Development ◽  
High Glucose ◽  
Oocyte Quality ◽  
Negative Energy ◽  
Developmental Competence ◽  
Moderate Increase ◽  
Developmental Potential ◽  
Normal Glucose ◽  
Low Glucose

Lipolytic metabolic conditions are traditionally associated with elevated non-esterified fatty acid (NEFA) concentrations, but may also be accompanied by hyperglycaemia in obesity or by hypoglycaemia during a negative energy balance status. Elevated NEFA concentrations disrupt oocyte and embryo development and quality, but little is known about whether the effects of lipolytic conditions on oocyte developmental competence are modulated by glucose availability. To answer this, bovine cumulus–oocyte complexes (COCs) were matured under different conditions: physiological NEFA (72 µM) and normal glucose (5.5 mM), pathophysiologically high NEFA (420 µM) and normal glucose, high NEFA and high glucose (9.9 mM), high NEFA and low glucose (2.8 mM). Developmental potential, cumulus expansion and metabolism of COCs exposed to high NEFA and low glucose were affected to a greater extent compared with COCs matured under high NEFA and high glucose conditions. High NEFA and high glucose conditions caused a moderate increase in oocyte reactive oxygen species compared with their high NEFA and low glucose or control counterparts. Blastocyst metabolism and the transcriptome of metabolic and oxidative stress-related genes were not affected. However, both lipolytic conditions associated with hyper- or hypoglycaemia led to surviving embryos of reduced quality with regards to apoptosis and blastomere allocation.

158 The Effect of Follicular Wave Phase at Time of Ovum Pick-Up on Bovine Oocyte Cytoplasmic Maturation and Developmental Competence

2018 ◽  
Vol 30 (1) ◽  
pp. 218
Author(s):  
B. A. Foster ◽  
F. A. Diaz ◽  
E. J. Gutierrez ◽  
K. R. Bondioli
Keyword(s):  
Embryo Development ◽  
Transvaginal Ultrasound ◽  
Oocyte Quality ◽  
Developmental Competence ◽  
Developmental Potential ◽  
Follicular Wave ◽  
Wave Phase ◽  
Oocyte Collection ◽  
Significant Difference

During oocyte collection, follicular wave phase is unknown, although differences in follicle environment may have dramatic effects on oocyte quality. This project was performed to determine whether oocyte collection during different phases of the follicular wave affects oocyte competence. Oocytes were collected via transvaginal ultrasound guided oocyte aspiration from 18 cows, at 4, 8, and 12 days following dominant follicle removal, representing follicle wave emergence, peak, and atresia, respectively (160, 314, and 273 oocytes, respectively). Once recovered, oocytes were graded and assigned to either being held as immature or matured in vitro for 24 h. Oocytes were then stained in Mitotracker deep red, fixed and stained with an anti-IP3R1 primary antibody and an Alexa Fluor 488-conjugated secondary antibody, before being stained with DAPI, to identify mitochondria, inositol triphosphate receptor 1 (IP3R1), and chromatin respectively. Mitochondria were analysed based on cytoplasmic distribution and classified as peripheral (immature), diffuse, central (mature), or sparse. Expression of IP3R1 was measured as corrected total cell fluorescence in Image J (National Institutes of Health, Bethesda, MD, USA). Staining patterns were analysed using ANOVA. A subset of the matured oocytes was stained with Fluo-3 to measure cytoplasmic calcium levels. These oocytes were then parthenogenetically activated before being imaged again to view changes in calcium levels, and presumptive embryos were cultured for 4 days. Fluo staining was measured as intensity levels (none, slight, moderate, high) and differences in development and stain levels were analysed using the Kruskal-Wallis test. Although mitochondria location was unaffected by collection day, it was significantly affected by maturation status (P = 0.0036). However, oocytes showed incomplete mitochondrial maturation, with mitochondria residing in the diffuse orientation in the majority of oocytes. Expression of IP3R1 appeared to be more sensitive to treatment. Expression significantly increased as meiosis proceeded (P = 0.0081) and there was a significant difference in expression between oocyte collection days (P = 0.0026). The interaction between collection day and maturation status also had a significant effect (P = 0.048), with mature oocytes showing an increase in IP3R1 expression, most notable in those collected on Day 4. Oocyte quality had a notable effect on the ability of oocytes to progress through meiosis (P = 0.054) and on mitochondrial location (P = 0.053), with AB oocytes showing better maturation parameters in both respects. Although the day of collection did not affect embryo development, Fluo stain intensity was an indicator of embryo developmental potential (P = 0.053), with oocytes having decreased potential to develop if the initial calcium levels were moderate to high. Results suggest that oocyte collection during wave emergence yields a slight advantage in oocyte quality. Although IP3R1, necessary for Ca2+ spikes during fertilization, indicates competence, high levels of cytoplasmic Ca2+ at the time of activation appear to be detrimental to embryo development.

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 &gt; 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 Improvement of quality of oocytes collected in the autumn by enhanced removal of impaired follicles from previously heat-stressed cows

Reproduction ◽  
2001 ◽  
pp. 737-744 ◽  
Author(s):  
Z Roth ◽  
A Arav ◽  
A Bor ◽  
Y Zeron ◽  
R Braw-Tal ◽  
...  
Keyword(s):  
Heat Stress ◽  
Embryo Development ◽  
Treated Group ◽  
Oocyte Quality ◽  
Control Group ◽  
Delayed Effect ◽  
Cleavage Rate ◽  
Lactating Cows ◽  
Summer Heat

The fertility of dairy cows decreases during the summer and remains low during the cooler autumn although the animals are no longer under heat stress. The aim of this study was to characterize a delayed effect of summer heat stress on oocyte quality in the autumn and to improve oocyte quality by enhanced removal of follicles damaged during the previous summer. Lactating cows (n = 16) were subjected to heat stress during the summer. In autumn, ovarian follicles (3-7 mm in diameter) were aspirated by an ultrasound-guided procedure during four consecutive oestrous cycles. Follicles were aspirated from control cows on day 4 and from treated cows on days 4, 7, 11 and 15 of each oestrous cycle. All cows received PGF(2alpha) and GnRH injections on days 19 and 21, respectively, and maintained cyclicity, as indicated by plasma progesterone concentrations. On day 4 of each cycle, the oocytes recovered were examined morphologically, matured and activated in vitro, and cultured for 8 days. In cycle 1 (early October) both groups showed low percentages of grade 1 oocytes, cleavage, four- and eight-cell embryos, morulae and parthenogenetic blastocysts. Subsequently, the number of grade 1 oocytes increased earlier (cycle 2) in treated than in control cows (cycle 3; P < 0.05). The cleavage rate in the control group remained relatively low throughout (32-58%), whereas in the treated group it increased from 40% (cycle 1) to 75% (cycles 3 and 4; P < 0.05). The number at each stage of embryo development increased slightly but remained low throughout in the control group, whereas in the treated group significant (P < 0.05) increases of all stages were observed in cycles 3 and 4. The results show a delayed effect of summer heat stress on oocyte quality and embryo development in the autumn. Enhanced removal of the impaired cohort of follicles led to earlier emergence of healthy follicles and high quality oocytes in the autumn.

The effects of brain-derived neurotrophic factor and metformin on in vitro developmental competence of bovine oocytes

Zygote ◽  
2009 ◽  
Vol 17 (3) ◽  
pp. 187-193 ◽  
Author(s):  
So Gun Hong ◽  
Goo Jang ◽  
Hyun Ju Oh ◽  
Ok Jae Koo ◽  
Jung Eun Park ◽  
...  
Keyword(s):  
Tyrosine Kinase ◽  
Embryo Development ◽  
Neurotrophic Factor ◽  
Brain Derived Neurotrophic Factor ◽  
Early Embryo ◽  
Developmental Competence ◽  
Blastocyst Development ◽  
Cell Stage ◽  
Significant Difference

SummaryBrain-derived neurotrophic factor (BDNF) signalling via tyrosine kinase B receptors may play an important role in ovarian development and function. It has been reported that metformin elevates the activity of Tyrosine kinase receptors and may amplify BDNF signalling. The objective of this study was to investigate the effect of BDNF during in vitro maturation (IVM) and/or in vitro culture (IVC) (Experiment 1), and to evaluate the collaborative effect of BDNF and metformin treatment on the developmental competence of bovine in vitro fertilized (IVF) embryos (Experiment 2). In Experiment 1, BDNF, which was added to our previously established IVM systems, significantly increased the proportions of MII oocytes at both 10 ng/ml (86.7%) and 100 ng/ml (85.4%) compared with the control (64.0%). However, there was no statistically significant difference in blastocyst development between the control or BDNF-supplemented groups. In Experiment 2, in order to investigate the effect of BDNF (10 ng/ml) and/or metformin (10−5 M) per se, TCM-199 without serum and hormones was used as the control IVM medium. The BDNF (48.3%) and BDNF plus metformin (56.5%) significantly enhanced the proportions of MII oocytes compared with the control (34.4%). Although, BDNF or metformin alone had no effect in embryo development, BDNF plus metformin significantly improved early embryo development to the 8–16-cell stage compared with the control (16.5 vs. 5.5%). In conclusion, the combination of BDNF and metformin may have a collaborative effect during the IVM period. These results could further contribute to the establishment of a more efficient bovine in vitro embryo production system.

scholarly journals Maturation of human oocytes in vitro and their developmental competence

Reproduction ◽  
2001 ◽  
pp. 51-75 ◽  
Author(s):  
A Trounson ◽  
C Anderiesz ◽  
G Jones
Keyword(s):  
Embryo Development ◽  
Oocyte Maturation ◽  
Growth Phase ◽  
Developmental Competence ◽  
Minimum Size ◽  
Success Rates ◽  
Human Oocytes ◽  
Maturation In Vitro

Complete maturation of oocytes is essential for the developmental competence of embryos. Any interventions in the growth phase of the oocyte and the follicle in the ovary will affect oocyte maturation, fertilization and subsequent embryo development. Oocyte size is associated with maturation and embryo development in most species examined and this may indicate that a certain size is necessary to initiate the molecular cascade of normal nuclear and cytoplasmic maturation. The minimum size of follicle required for developmental competence in humans is 5-7 mm in diameter. Maturation in vitro can be accomplished in humans, but is associated with a loss of developmental competence unless the oocyte is near completion of its preovulatory growth phase. This loss of developmental competence is associated with the absence of specific proteins in oocytes cultured to metaphase II in vitro. The composition of culture medium used successfully for maturation of human oocytes is surprisingly similar to that originally developed for maturation of oocytes in follicle culture in vitro. The presence of follicle support cells in culture is necessary for the gonadotrophin-mediated response required to mature oocytes in vitro. Gonadotrophin concentration and the sequence of FSH and FSH-LH exposure may be important for human oocytes, particularly those not exposed to the gonadotrophin surge in vivo. More research is needed to describe the molecular and cellular events, the presence of checkpoints and the role of gene expression, translation and protein uptake on completing oocyte maturation in vitro and in vivo. In the meantime, there are very clear applications for maturing oocytes in human reproductive medicine and the success rates achieved in some of these special applications are clinically valuable.

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