The expression level of SOX2 at the blastocyst stage regulates the developmental capacity of bovine embryos up to day-13 of in vitro culture

Zygote ◽  
2019 ◽  
Vol 27 (6) ◽  
pp. 398-404 ◽  
Author(s):  
A.E. Velásquez ◽  
D. Veraguas ◽  
J. Cabezas ◽  
J. Manríquez ◽  
F.O. Castro ◽  
...  
Keyword(s):  
Blastocyst Stage ◽  
The Other ◽  
Embryo Survival ◽  
Gene Markers ◽  
Developmental Potential ◽  
Pluripotency Markers ◽  
Negative Effect ◽  
Developmental Capacity

SummaryQuality of in vitro-produced embryos is influenced by changes in gene expression in response to adverse conditions. Gene markers for predicting ‘good embryos’ do not exist at present. We propose that the expression of pluripotency markers OCT4–SOX2–NANOG in D9 (day 9) bovine demi-embryos correlated with development at D13 (day 13). Day 8 in vitro-produced blastocysts were split in two cloned halves, one half (D9) was subjected to analysis of pluripotency markers and the other was kept in culture until D13 of development. Embryo development was scored and correlated with its own status at D9 and assigned to one of two categories: G1, arrested/dead; or G2, development up to D13. SOX2 and NANOG expression levels were significantly higher in embryos from G1 and there was also negative correlation between SOX2 and embryo survival to D13 (G3; r = −0.37; P = 0.03). We observed a significant reduction in the expression of the three studied genes from D9 to D13. Furthermore, there was a correlation between the expression of pluripotency markers at D9 and embryo diameter and the expression of trophoblastic markers at D13 (TP1–EOMES–FGF4–CDX2–TKDP1). Finally, the quotient between the relative expression of SOX2 and OCT4 in the D9 blastocysts from G1 and G2 showed that embryos that were considered as competent (G2) had a quotient close to one, while the other group had a quotient of 2.3 due to a higher expression of SOX2. These results might indicate that overexpression of SOX2 at the blastocyst stage had a negative effect on the control of embryonic developmental potential.

Relationship between bovine oocyte morphology and in vitro developmental potential

Zygote ◽  
2006 ◽  
Vol 14 (1) ◽  
pp. 53-61 ◽  
Author(s):  
Masashi Nagano ◽  
Seiji Katagiri ◽  
Yoshiyuki Takahashi
Keyword(s):  
Small Diameter ◽  
Blastocyst Stage ◽  
Cortical Granules ◽  
Developmental Potential ◽  
Developmental Capacity ◽  
Sperm Penetration ◽  
Developmental Rates ◽  
Large Clusters

We investigated the relationship between the morphology of oocytes collected from small antral follicles and their developmental capacity. Immature oocytes were classified into seven groups and cultured in vitro for maturation (IVM), fertilization (IVF) and development to blastocysts (IVC). After IVF, sperm penetration and normal fertilization rates were higher in the oocytes whose cytoplasm appeared brown. The rate of polyspermy was highest in the oocytes whose cytoplasm was black. After IVC, the rates of cleavage and of development to the blastocyst stage were also higher in the brown oocytes. Although the oocytes with dark clusters in a pale cytoplasm showed lower cleavage rates, cleaved zygotes had high developmental rates the same as the oocytes with a brown cytoplasm. Transmission electron microscopy showed that the oocytes with a pale or black cytoplasm had organelles arranged differently from other oocytes before IVM. Most of the oocytes with a brown and homogeneous cytoplasm or small diameter had the characteristics of immature cytoplasm (large clusters of cortical granules) even after IVM. On the other hand, the brown oocytes with a dark zone at the periphery or with dark clusters showed the same arrangement of organelles as in vivo matured oocytes. The oocytes with a pale or black cytoplasm appeared to be degenerating and/or ageing. In conclusion, a dark ooplasm indicates an accumulation of lipids and good developmental potential, while a light-coloured ooplasm indicates a low density of organelles and poor developmental potential. A black ooplasm indicates ageing and low developmental potential.

Morphokinetics and in vitro developmental potential of monopronucleated ICSI zygotes until the blastocyst stage

Zygote ◽  
2020 ◽  
Vol 28 (3) ◽  
pp. 217-222
Author(s):  
Silvia Mateo ◽  
Francesca Vidal ◽  
Beatriz Carrasco ◽  
Ignacio Rodríguez ◽  
Buenaventura Coroleu ◽  
...  
Keyword(s):  
Blastocyst Stage ◽  
Control Group ◽  
Study Group ◽  
Comprehensive Understanding ◽  
Developmental Potential ◽  
Morphokinetic Parameters ◽  
Developmental Capacity ◽  
Blastocyst Rate ◽  
Kinetics Of

SummaryThe aim of this study was to provide a more comprehensive understanding of 1PN intracytoplasmic sperm injection (ICSI) zygotes. To achieve this objective, we assessed whether all 1PN-derived embryos showed a similar morphokinetic pattern, and if the morphokinetic behaviour of 1PN-derived embryos was comparable with that of 2PN-derived embryos. In total, 149 1PN ICSI zygotes (study group) and 195 2PN ICSI zygotes (control group) were included in the study. Embryo development potential was evaluated in terms of blastocyst rate. Morphokinetic parameters, including the pronucleus diameter and kinetics of in vitro development, were also analyzed. Embryos derived from 1PN ICSI zygotes showed impaired development compared with 2PN-derived embryos, with blastocyst rates of 28.9% and 67.2%, respectively. The diameter of the pronucleus of 1PN zygotes was larger than that of 2PN zygotes. When compared with 2PN-derived embryos, those derived from 1PN zygotes had a visible pronucleus for a shorter time, in addition to a longer syngamy time and slower kinetic behaviour from two to nine cells. When 1PN-derived blastocysts and 2PN-derived blastocysts were compared, the developmental kinetics were similar in both groups, except for a delayed and longer duration of the compaction phase in 1PN-derived embryos. In conclusion, monopronucleated ICSI zygotes present differences in developmental capacity and morphokinetic behaviour compared with 2PN ICSI zygotes, showing particular morphokinetic parameters related to pronucleus formation. Only the 1PN ICSI-derived embryos that reached the blastocyst stage have similar morphokinetic development to blastocysts from 2PN zygotes.

94 EFFICIENT BOVINE EMBRYO SPLITTING FOR GENE EXPRESSION AND IN VIVO DEVELOPMENT STUDIES

2014 ◽  
Vol 26 (1) ◽  
pp. 161
Author(s):  
A. Velasquez ◽  
D. Veraguas ◽  
F. O. Castro ◽  
J. F. Cox ◽  
L. l. Rodriguez-Alvarez
Keyword(s):  
Gene Expression ◽  
Expression Pattern ◽  
Gene Expression Pattern ◽  
Blastocyst Stage ◽  
Embryo Morphology ◽  
Bovine Embryo ◽  
Gene Markers ◽  
Developmental Potential

It is known that embryos produced in vitro are less competent than their in vivo-derived counterparts. When embryos are produced or manipulated in vitro, their developmental potential decreases significantly, which impinges upon the production of viable offspring. In bovines, embryos that will be transferred to a surrogate mother are selected at the blastocysts stage using noninvasive methods, such as their morphological features. However, many of those embryos are not able to implant or to maintain a normal pregnancy because embryo morphology does not reflect its developmental potential and a correct gene expression pattern that support a normal development. It seems that the ideal method for embryo selection would be based on the screening of gene markers that correlate with successful pregnancy after embryo transfer. In that sense, we have proposed an approach to characterise gene expression pattern of early (Day 7) bovine blastocysts and to correlate this gene expression with further developmental potential in vivo, i.e. upon elongation until Day 17. For that, it was established an efficient method to produce identical and viable hemi-embryos by splitting IVF bovine blastocysts in order to set the expression profile of certain genes in one hemi-embryo at blastocyst stage, while the counterpart embryo elongates in vivo for 10 days. A total of 129 blastocysts were split. Six groups of blastocysts were used for splitting and the results compared: 1) Day-7 early blastocysts (n = 20); 2) Day-7 expanded blastocysts (n = 25); 3) Day-7 hatched blastocysts (n = 17); 4) Day-8 early blastocysts (n = 10); 5) Day-8 expanded blastocysts (n = 12); and 6) Day-8 hatched blastocysts (n = 45). Hemi-embryos derived from day-8 grade I and well expanded blastocysts had the greatest survival rate, in vitro re-expansion (67.7%; P < 0.05) and both hemi-embryos conserved a normal morphology with a total cell number over 80 after 6 h in culture. Also both hemi-embryos at blastocyst stage showed homogeneous expression pattern of the genes OCT4, SOX2, NANOG, CDX2, ACTB, and GAPDH (P < 0.05). Finally, the in vivo survival of hemi-embryos was assessed and compared with nonsplit embryos (control) by transferring to recipient cow and collecting at Day 17 of development. For this, hemi-embryos derived from Day-8 hatched blastocyst were used. From 14 transferred hemi-embryos, 5 (35.7%) were collected, and 9 elongated from 17 controls were recovered (52.9%). Also the elongation rate was significantly lower in hemi-embryos than in control; the length of hemi-embryos had a range between 1 and 5 cm, whereas 60% of the control embryos were longer than 10 cm. Our results provide an initial approach to study the correlation among the gene expression characteristics of early bovine embryos with their further development. However, it seems that embryo splitting hampers their elongation in vivo. It might be possible that the development of split embryos is retarded because of manipulation. This work was partially supported by Fondecyt grant no. 11100082 from the Ministry of Education of Chile.

scholarly journals Insulin exposure during in vitro bovine oocyte maturation changes blastocyst gene expression and developmental potential

2017 ◽  
Vol 29 (5) ◽  
pp. 876 ◽  
Author(s):  
Denise Laskowski ◽  
Ylva Sjunnesson ◽  
Patrice Humblot ◽  
Marc-André Sirard ◽  
Göran Andersson ◽  
...  
Keyword(s):  
Gene Expression ◽  
Oocyte Maturation ◽  
Quantitative Polymerase Chain Reaction ◽  
Blastocyst Stage ◽  
Specific Gene ◽  
Bovine Oocyte ◽  
Developmental Potential ◽  
Metabolic Imbalance ◽  
Negative Effect

Metabolic imbalance impairs fertility, because changes in concentrations of metabolites and hormones in the blood and follicular fluid create an unfavourable environment for early embryonic development. Insulin is a key metabolic hormone known for its effects on fertility: insulin concentrations are increased during energy balance disturbances in diabetes or metabolic syndrome. Still, insulin is frequently used at supraphysiological concentrations for embryo in vitro culture with unknown consequences for the developmental potential of the offspring. In the present study we investigated the effects of insulin exposure during in vitro bovine oocyte maturation on developmental rates, embryo quality and gene expression. Supplementation of the maturation media with insulin at 10 or 0.1 µg mL–1 decreased blastocyst rates compared with an insulin-free control (19.8 ± 1.3% and 20.4 ± 1.3% vs 23.8 ± 1.3%, respectively; P < 0.05) and led to increased cell numbers (nearly 10% more cells on Day 8 compared with control; P < 0.05). Transcriptome analysis revealed significant upregulation of genes involved in lipid metabolism, nuclear factor (erythroid-derived 2)-like 2 (NRF2) stress response and cell differentiation, validated by quantitative polymerase chain reaction. To conclude, the results of the present study demonstrate that insulin exposure during in vitro oocyte maturation has a lasting effect on the embryo until the blastocyst stage, with a potential negative effect in the form of specific gene expression perturbations.

Developmental capacity, energy metabolism and ultrastructure of mature oocytes from prepubertal and adult sheep

1996 ◽  
Vol 8 (7) ◽  
pp. 1029 ◽  
Author(s):  
JK O'Brien ◽  
D Dwarte ◽  
JP Ryan ◽  
WM Maxwell ◽  
G Evans
Keyword(s):  
Volume Fraction ◽  
Blastocyst Stage ◽  
Glutamine Metabolism ◽  
Cortical Granules ◽  
Developmental Potential ◽  
Adult Sheep ◽  
Ultrastructural Studies ◽  
Developmental Capacity

Development to the blastocyst stage was assessed for oocytes obtained from prepubertal and adult sheep matured and fertilized in vitro. The proportion of cleaved oocytes reaching the blastocyst stage was significantly lower for oocytes derived from prepubertal sheep than for those from adult sheep (7.4% and 24.6% respectively). There were no differences in the metabolism of glucose, glutamine or pyruvate between oocytes matured in vivo and in vitro, or of glucose or pyruvate between oocytes from prepubertal and adult sheep. Glutamine metabolism by mature oocytes from prepubertal sheep was significantly lower than that by oocytes from adult sheep. Ultrastructural studies revealed no differences in the morphology of cytoplasmic organelles of oocytes matured in vitro from prepubertal and adult sheep, but differences in the volume fraction and size of mitochondria and cortical granules were observed. These data suggest that mature oocytes from prepubertal sheep do not possess the developmental potential of their adult-derived counterparts, and this phenomenon may be associated with metabolic and ultrastructural anomalies.

Comparison of glucose metabolism in in vivo- and in vitro-matured tammar wallaby oocytes and its relationship to developmental potential following intracytoplasmic sperm injection

2004 ◽  
Vol 16 (6) ◽  
pp. 617 ◽  
Author(s):  
Genevieve M. Magarey ◽  
Karen E. Mate
Keyword(s):  
Glucose Metabolism ◽  
Intracytoplasmic Sperm Injection ◽  
Tammar Wallaby ◽  
Blastocyst Stage ◽  
In Vitro Fertilisation ◽  
Cell Stage ◽  
Developmental Potential ◽  
Developmental Capacity

Although marsupial oocytes undergo nuclear maturation in vitro, there is, at present, no indication of their developmental potential, largely owing to the lack of in vitro fertilisation and related technologies for marsupials. Glucose metabolism has proven a useful indicator of oocyte cytoplasmic maturation and developmental potential in several eutherian species. Therefore, the aims of the present study were to compare: (1) the rates of glycolysis and glucose oxidation in immature, in vitro-matured and in vivo-matured tammar wallaby oocytes; and (2) the metabolic rate of individual oocytes with their ability to form pronuclei after intracytoplasmic sperm injection. The rates of glycolysis measured in immature (2.18 pmol oocyte–1 h–1), in vitro-matured (0.93 pmol oocyte–1 h–1) and in vivo-matured tammar wallaby oocytes (0.54 pmol oocyte–1 h–1) were within a similar range to values obtained in eutherian species. However, unlike the trend observed in eutherian oocytes, the glycolytic rate was significantly higher in immature oocytes compared with either in vivo- or in vitro-matured oocytes (P < 0.001) and significantly higher in in vitro-matured oocytes compared with in vivo-matured oocytes (P < 0.001). No relationship was identified between glucose metabolism and the developmental capacity of oocytes after intracytoplasmic sperm injection when assessed after 17–19 h. Oocytes that became fertilised (two pronuclei) or activated (one or more pronucleus) were not distinguished from others by their metabolic rates. Longer culture after intracytoplasmic sperm injection (e.g. blastocyst stage) may show oocyte glucose metabolism to be predictive of developmental potential; however, culture to the single-cell stage did not reveal any significant differences in normally developing embryos.

147 QUALITY OF PORCINE EMBRYOS CULTURED WITH HYALURONAN

2010 ◽  
Vol 22 (1) ◽  
pp. 232
Author(s):  
B. Gajda ◽  
I. Grad ◽  
E. van der Tuin ◽  
Z. Smorag
Keyword(s):  
Cell Number ◽  
Blastocyst Stage ◽  
Apoptotic Index ◽  
Total Cell ◽  
Total Cell Number ◽  
Developmental Potential ◽  
Group 2 ◽  
Group 1

Hyaluronan (HA) is a high molecular weight polysaccharide found in the mammalian follicular, oviduct, and uterine fluids. When HA is added in maturation and culture media, it improves the developmental potential of bovine (Stojkovic M et al. 2002 Reproduction 124, 141-153; Palasz AT et al. 2008 Zygote 16, 39-47), and porcine oocytes (Sato E et al. 1990 Mol. Reprod. Dev. 26, 391-397) and embryos (Miyano T et al. 1994 Theriogenology 41, 1299-1305). Physiological concentration of HA in follicular, oviductal, and uterine fluids of pigs range from 0.04 to 1.83 mg mL-1 (Kano K et al. 1998 Biol. Reprod. 58, 1226-1232). The aim of the present study was to investigate the effect of different concentrations of HA on the development and quality of cultured porcine embryos. Zygotes from superovulated pigs were cultured in vitro in NCSU-23 medium supplemented with BSA and 0 mg mL-1 (control group), 0.25 mg mL-1 (Exp. Group 1), and 0.5 mg mL-1 (Exp. Group 2) of HA (Animal Pharma BV). Experiments were replicated 3 times with 30 to 40 embryos per each treatment group. Embryos were cultured up to the blastocyst stage at 39°C in an atmosphere of 5% CO2 in air, in 4-well plastic dishes, which contained approximately 0.8 mL of the NCSU-23 medium. Embryo quality criteria were cleavage (on Day 2 after in vitro culture), morula (on Day 4) and blastocyst (on Days 6 to 8) rates, total cell number per blastocyst, and degree of apoptosis (on Day 7) assessed by TUNEL method. Results were analyzed by ANOVA test. There was no difference in percentage of cleaved embryos between control and treated Group 1 and 2.The proportion of embryos developed to the morula and blastocyst stage was 80.0 and 60.0% for Group 1 (0.25 mg of HA), 73.7 and 44.7% for Group 2 (0.5 mg of HA), and 73.4 and 46.7% for control, respectively (difference NS). Supplementation with HA did not increase the cell number of the blastocysts but significantly reduced number of apoptotic nuclei from 2.0 for control to 0.7 (P < 0.01) and 0.6 (P < 0.01) for Group 1 and 2, respectively, and apoptotic index from 9.70 for control to 3.01 (P < 0.05) and 1.95 (P < 0.05) for Group 1 and 2, respectively. These results indicate that supplementation of culture medium NCSU-23 with HA improves the quality (assessed by apoptotic index) of pig embryos but does not increase the total cell number in pig blastocysts as reported by Kim HS et al. 2005 (Theriogenology 63, 1167-1180). However, further research to test the HA’s effect on cryopreservation of in vitro and in vivo produced pig embryos are needed.

scholarly journals 117 CYTOPLASMIC FACTORS INFLUENCE DEVELOPMENTAL POTENTIAL OF SAMP1/Yit MOUSE EMBRYOS

2005 ◽  
Vol 17 (2) ◽  
pp. 209
Author(s):  
J. Otsuka ◽  
H. Funabashi ◽  
T. Kono
Keyword(s):  
Blastocyst Stage ◽  
Development Rate ◽  
Mouse Embryos ◽  
The Other ◽  
Nuclear Transplantation ◽  
Chi Square ◽  
Developmental Potential ◽  
Reconstructed Embryos

Nuclear transplantation is an efficient means to investigate nucleo-cytoplasmic interactions of mammalian embryos during early development. A recent study has shown that the developmental potential of embryos is affected by the type of cytoplasm. The SAMP1/Yit mouse, an inbred strain that develops spontaneous chronic ileitis resembling Crohn's disease (Matsumoto S 1999 Bioscience Microflora 18, 1–9), has poor reproductive performance, and the developmental ability of embryos is low (unpublished data). Therefore we need to enhance productivity of the SAMP1/Yit mouse. Recently it was reported that cytoplasm of F1 mouse egg supported the development of embryos which have low developmental ability (Muggleton-Harris A et al. 1982 Nature 299, 460–462). In the present study, we examined the influences of the nucleus and cytoplasm on the development of reconstructed embryos in vitro and in vivo, using reciprocal nuclear transplantation between SAMP1/Yit and B6P1F1 (C57BL/6J × SAMP1/Yit) mouse embryos. We evaluated the developmental ability of reconstructed embryos by the development rate into blastocysts in vitro and by the rate of offspring after transfer of blastocysts to recipient mice. Pronuclear transplantation was carried out as reported previously (McGrath J and Solter D 1983 Science 220, 1300–1302). Briefly, karyoplasts from one-cell SAMP1/Yit embryos were introduced into enucleated B6P1F1 zygotes (SAMP1/B6P1F1) and fused by addition of inactivated HVJ (2700 U L−1). The other group of reconstructed embryos (B6P1F1/SAMP1) was manipulated similarly. After fusion, reconstructed embryos were cultured in drops of KSOM medium for 120 h at 37°C in 5% CO2 in humidified air. Some reconstructed and control (unmanipulated) embryos that developed to the blastocyst stage were transferred to the uteri of recipient mice. Data were compared using chi-square test; differences were considered significant at P < 0.01. The development rate of [SAMP1/B6P1F1] embryos to the blastocyst stage was significantly (P < 0.01) higher (75.0%) than that of SAMP1/Yit controls (39.1%). The rate of offspring in [SAMP1/B6P1F1] was also significantly (P < 0.01) higher (47.5%) than that of SAMP1/Yit controls (22.1%). On the other hand, [B6P1F1/SAMP1] embryos showed low developmental potential compared to B6P1F1 control embryos. These results indicate that the source of the cytoplasm strongly influences the development of reconstructed embryos containing SAMP1/Yit karyoplasts. Table 1.

Novel REST Truncation Mutations Causing Hereditary Gingival Fibromatosis

2021 ◽  
pp. 002203452199662
Author(s):  
J.T. Chen ◽  
C.H. Lin ◽  
H.W. Huang ◽  
Y.P. Wang ◽  
P.C. Kao ◽  
...  
Keyword(s):  
Nuclear Localization ◽  
Genetic Disorder ◽  
Dominant Negative ◽  
Dominant Negative Effect ◽  
Wild Type ◽  
Negative Effect ◽  
Localization Signal ◽  
Gingival Fibromatosis

Hereditary gingival fibromatosis (HGF) is a rare genetic disorder featured by nonsyndromic pathological overgrowth of gingiva. The excessive gingival tissues can cause dental, masticatory, and phonetic problems, which impose severe functional and esthetic burdens on affected individuals. Due to its high recurrent rate, patients with HGF have to undergo repeated surgical procedures of gingival resection, from childhood to adulthood, which significantly compromises their quality of life. Unraveling the genetic etiology and molecular pathogenesis of HGF not only gains insight into gingival physiology and homeostasis but also opens avenues for developing potential therapeutic strategies for this disorder. Recently, mutations in REST (OMIM *600571), encoding a transcription repressor, were reported to cause HGF (GINGF5; OMIM #617626) in 3 Turkish families. However, the functions of REST in gingival homeostasis and pathogenesis of REST-associated HGF remain largely unknown. In this study, we characterized 2 HGF families and identified 2 novel REST mutations, c.2449C>T (p.Arg817*) and c.2771_2793dup (p.Glu932Lysfs*3). All 5 mutations reported to date are nonsenses or frameshifts in the last exon of REST and would presumably truncate the protein. In vitro reporter gene assays demonstrated a partial or complete loss of repressor activity for these truncated RESTs. When coexpressed with the full-length protein, the truncated RESTs impaired the repressive ability of wild-type REST, suggesting a dominant negative effect. Immunofluorescent studies showed nuclear localization of overexpressed wild-type and truncated RESTs in vitro, indicating preservation of the nuclear localization signal in shortened proteins. Immunohistochemistry demonstrated a comparable pattern of ubiquitous REST expression in both epithelium and lamina propria of normal and HGF gingival tissues despite a reduced reactivity in HGF gingiva. Results of this study confirm the pathogenicity of REST truncation mutations occurring in the last exon causing HGF and suggest the pathosis is caused by an antimorphic (dominant negative) disease mechanism.

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

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