020. IN VITRO MATURATION OF FARM ANIMALS OOCYTES: A USEFUL TOOL FOR INVESTIGATING THE MECHANISMS LEADING TO FULL TERM DEVELOPMENT

2009 ◽  
Vol 21 (9) ◽  
pp. 7
Author(s):  
F. Gandolfi ◽  
T. Brevini
Keyword(s):  
Large Body ◽  
Genetic Material ◽  
Oocyte Quality ◽  
Full Term ◽  
Farm Animals ◽  
Ongoing Research ◽  
Developmental Potential ◽  
Oocyte Competence ◽  
Amount Of Knowledge

Due to logistical and economical reasons assisted reproduction of domestic animals has been based mostly on the use of oocytes isolated from ovaries collected at the slaughterhouse. In order to propagate valuable or rare genetic material, perform somatic cell nuclear transfer, generate genetically modified animals it was essential to obtain fully competent oocytes that would allow full term development of the in vitro produced embryos. Such demanding need has soon made clearly evident the crucial role played by oocyte quality, how easy it is to compromise its developmental potential and the fact that it is impossible to restore it once it has been lost. Almost three decades after the first bovine, sheep, goat, horse and pig in vitro generated offsprings were born, a large body of information has accumulated on the mechanisms regulating oocyte competence and on how the latter may be preserved during all the required manipulations. The amount of knowledge is far from being complete and many laboratories are actively working to further expand it. In this review we will highlight the aspects of the ongoing research in which we have been actively involved.

RFD Award Lecture 2009.In vitro maturation of farm animal oocytes: a useful tool for investigating the mechanisms leading to full-term development

2010 ◽  
Vol 22 (3) ◽  
pp. 495 ◽  
Author(s):  
Fulvio Gandolfi ◽  
Tiziana A. L. Brevini
Keyword(s):  
In Vitro Maturation ◽  
Large Body ◽  
Genetic Material ◽  
Oocyte Quality ◽  
Full Term ◽  
Ongoing Research ◽  
Developmental Potential ◽  
Oocyte Competence ◽  
Amount Of Knowledge

Due to logistical and economic reasons, assisted reproduction of domestic animals has been based mostly on the use of oocytes isolated from ovaries collected at the slaughterhouse. In order to propagate valuable or rare genetic material, perform somatic cell nuclear transfer or generate genetically modified animals, it is essential to obtain fully competent oocytes that will allow full-term development of the in vitro-produced embryos. Such a need makes clear the crucial role played by oocyte quality. In fact, it is easy to compromise the oocyte’s developmental potential but it is impossible to restore once it has been lost. Almost three decades after the first cow, sheep, goat, horse and pig in vitro-generated offspring were born, a large body of information has accumulated on the mechanisms regulating oocyte competence and on how the latter may be preserved during all the required manipulations. The amount of knowledge is far from complete and many laboratories are actively working to further expand it. In this review we will highlight the aspects of the ongoing research in which we have been actively involved.

scholarly journals Cellular and Molecular Events that Occur in the Oocyte during Prolonged Ovarian Storage in Sheep

Animals ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 2414
Author(s):  
Alicia Martín-Maestro ◽  
Irene Sánchez-Ajofrín ◽  
Carolina Maside ◽  
Patricia Peris-Frau ◽  
Daniela-Alejandra Medina-Chávez ◽  
...  
Keyword(s):  
Dna Fragmentation ◽  
Saline Solution ◽  
Cumulus Cell ◽  
Small Ruminants ◽  
Oocyte Quality ◽  
Developmental Competence ◽  
Developmental Potential ◽  
Oocyte Competence ◽  
Cell Parameters

For the past two decades, there has been a growing interest in the application of in vitro embryo production (IVP) in small ruminants such as sheep. To improve efficiency, a large number abattoir-derived ovaries must be used, and long distances from the laboratory are usually inevitable when adult animals are used. In that scenario, prolonged sheep ovary transportation may negatively affect oocyte developmental competence. Here, we evaluated the effect of ovary storage time (3, 5, 7, 9, 11 and 13 h) and the medium in which they were transported (TCM199 and saline solution) on oocyte quality. Thus, live/dead status, early apoptosis, DNA fragmentation, reduced glutathione (GSH) and reactive oxygen species (ROS) content, caspase-3 activity, mitochondrial membrane potential and distribution, and relative abundance of mRNA transcript levels were assessed in oocytes. After in vitro maturation (IVM), cumulus cell viability and quality, meiotic and fertilization competence, embryo rates and blastocyst quality were also evaluated. The results revealed that, after 7 h of storage, oocyte quality and developmental potential were significantly impaired since higher rates of dead oocytes and DNA fragmentation and lower rates of viable, matured and fertilized oocytes were observed. The percentage of cleavage, blastocyst rates and cumulus cell parameters (viability, active mitochondria and GSH/ROS ratio) were also decreased. Moreover, the preservation of ovaries in medium TCM199 had a detrimental effect on cumulus cells and oocyte competence. In conclusion, ovary transport times up to 5 h in saline solution are the most adequate storage conditions to maintain oocyte quality as well as developmental capacity in sheep. A strategy to rescue the poor developmental potential of stored oocytes will be necessary for successful production of high-quality embryos when longer ovarian preservation times are necessary.

scholarly journals Mitochondrial enrichment in infertile patients: a review of different mitochondrial replacement therapies

2021 ◽  
Vol 15 ◽  
pp. 263349412110235
Author(s):  
Cristina Rodríguez-Varela ◽  
Sonia Herraiz ◽  
Elena Labarta
Keyword(s):  
Stem Cells ◽  
Genetic Material ◽  
External Source ◽  
Oocyte Quality ◽  
Third Party ◽  
In Vitro Fertilisation ◽  
Mitochondrial Activity ◽  
Mitochondrial Transfer ◽  
Infertile Patients

Poor ovarian responders exhibit a quantitative reduction in their follicular pool, and most cases are also associated with poor oocyte quality due to patient’s age, which leads to impaired in vitro fertilisation outcomes. In particular, poor oocyte quality has been related to mitochondrial dysfunction and/or low mitochondrial count as these organelles are crucial in many essential oocyte processes. Therefore, mitochondrial enrichment has been proposed as a potential therapy option in infertile patients to improve oocyte quality and subsequent in vitro fertilisation outcomes. Nowadays, different options are available for mitochondrial enrichment treatments that are encompassed in two main approaches: heterologous and autologous. In the heterologous approach, mitochondria come from an external source, which is an oocyte donor. These techniques include transferring either a portion of the donor’s oocyte cytoplasm to the recipient oocyte or nuclear material from the patient to the donor’s oocyte. In any case, this approach entails many ethical and safety concerns that mainly arise from the uncertain degree of mitochondrial heteroplasmy deriving from it. Thus the autologous approach is considered a suitable potential tool to improve oocyte quality by overcoming the heteroplasmy issue. Autologous mitochondrial transfer, however, has not yielded as many beneficial outcomes as initially expected. Proposed mitochondrial autologous sources include immature oocytes, granulosa cells, germline stem cells, and adipose-derived stem cells. Presently, it would seem that these autologous techniques do not improve clinical outcomes in human infertile patients. However, further trials still need to be performed to confirm these results. Besides these two main categories, new strategies have arisen for oocyte rejuvenation by improving patient’s own mitochondrial function and avoiding the unknown consequences of third-party genetic material. This is the case of antioxidants, which may enhance mitochondrial activity by counteracting and/or preventing oxidative stress damage. Among others, coenzyme-Q10 and melatonin have shown promising results in low-prognosis infertile patients, although further randomised clinical trials are still necessary.

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 324SPHINGOSINE-1-PHOSPHATE PROTECTS CULTURED BOVINE OOCYTES FROM PHYSIOLOGICALLY RELEVANT THERMAL STRESS

2004 ◽  
Vol 16 (2) ◽  
pp. 282 ◽  
Author(s):  
Z. Roth ◽  
P.J. Hansen
Keyword(s):  
Thermal Stress ◽  
Heat Shock ◽  
Blastocyst Stage ◽  
Caspase Activity ◽  
Blastocyst Development ◽  
Cleavage Rate ◽  
Developmental Potential ◽  
Oocyte Competence ◽  
Cell Death Pathway

Sphingosine-1-phosphate (S1P) is a sphingolipid metabolite that can block the sphingomyelin cell-death pathway by suppressing ceramide-induced apoptosis. The present study was performed to test whether S1P protects oocytes from heat shock during in vitro maturation. Cumulus-oocyte complexes obtained by slicing follicles were placed in maturation medium with or without 50nM S1P and cultured at 38.5°C (CON) or 41°C (41C) for the first 12h of maturation. Incubation during the last 10h of maturation (22-h total maturation time), fertilization, and embryonic development were performed at 38.5°C and 5% (v/v) CO2. Blastocyst development was recorded at 8 days post-insemination (dpi) and activity of group II caspases in 8-day blastocysts was determined using a fluoroprobe, PhiPhiLux-G1D2 (OncoImmunin, Gaithersburg, MD, USA). Data were analysed by least-squares ANOVA with the GLM procedure of SAS. Percentage data were subjected to arcsin transformation before analysis. Exposure of oocytes to thermal stress during the first 12h of maturation reduced cleavage rate (P<0.01) and the number of oocytes developing to the blastocyst stage (P<0.04). There was a temperature x S1P interaction for cleavage rate (P<0.03) because S1P blocked effects of thermal stress on cleavage rate. Without S1P, the percentage of oocytes that cleaved by 3 dpi were 83.6±2.7% and 65.8±2.7% for CON and 41C, respectively. In the presence of S1P, percent cleavage was 86.7±2.7% and 83.9±2.7% for CON and 41C, respectively. There was a trend (P=0.06) for a temperature x S1P interaction for percent oocytes developing to blastocyst stage because S1P blocked effects of heat shock on development. Without S1P, the percentages of oocytes that developed to the blastocyst stage were 28.7±3.0% and 15.2±3.0% for CON and 41C, respectively. In the presence of S1P, percent blastocysts were 24.3±3.4% and 23.9±3.0% for CON and 41C, respectively. When development was expressed as percentage of cleaved embryos, however, there were no effects of temperature, S1P, or temperature x S1P on percent development to the blastocyst stage. Blastocyst caspase activity was not affected by temperature or S1P. In summary, exposure to physiologically relevant thermal stress during the first 12h of maturation has a deleterious effect on oocyte competence and this effect can be reduced by S1P. The fact that heat shock reduced the percentage of oocytes but not the percentage of cleaved embryos that became blastocysts suggests that oocytes that survive effects of heat shock and cleave have normal potential to develop to the blastocyst stage. Moreover, since heat shock did not affect caspase activity, it is likely that blastocysts from heat-shocked oocytes have normal developmental potential, at least as determined by caspase activity. Support: BARD FI-330-2002 and USDA Grants 2002-35203-12664 and 2001-52101-11318.

The analysis of chromatin organisation allows selection of mouse antral oocytes competent for development to blastocyst

Zygote ◽  
2002 ◽  
Vol 10 (1) ◽  
pp. 73-78 ◽  
Author(s):  
Maurizio Zuccotti ◽  
Rubén H. Ponce ◽  
Michele Boiani ◽  
Stefano Guizzardi ◽  
Paolo Govoni ◽  
...  
Keyword(s):  
Developmental Competence ◽  
Farm Animals ◽  
Cell Stage ◽  
Developmental Potential ◽  
Different Types ◽  
Chromatin Organisation ◽  
Selection For ◽  
Gamete Selection ◽  
Selection Of

Mouse antral oocytes can be classified in two different types termed SN or NSN oocytes, depending on the presence or absence, respectively, of a ring of Hoechst 33342-positive chromatin surrounding the nucleolus. The aim of the present study was to test the developmental competence to blastocyst of the two types of oocytes. Here we show that following isolation, classification and culture of cumulus-free antral oocytes, 14.7% and 74.5% of NSN and SN oocytes, respectively, reached the metaphase II stage. When fertilised and further cultured none of the metaphase II NSN oocytes developed beyond the 2-cell stage whilst 47.4% of the metaphase II SN oocytes reached the 4-cell stage and 18.4% developed to blastocyst. The findings reported in this paper may contribute to improved procedures of female gamete selection for in vitro fertilisation of humans and farm animals. Furthermore, the selection of oocytes with better developmental potential may be of interest for studies on nuclear/cytoplasm interaction, particularly in nuclear-transfer experiments.

Oocytes from gilts of domestic pig (Sus scrofa domesticus) and wild boar (Sus scrofa) species exhibit similar developmental potential during in vitro maturation

1998 ◽  
Vol 1998 ◽  
pp. 178-178
Author(s):  
N.S. Prathalingam ◽  
K. Rust ◽  
M.E. Staines ◽  
G.J. McCallum ◽  
S.A. Edwards ◽  
...  
Keyword(s):  
Wild Boar ◽  
Sus Scrofa ◽  
In Vitro Maturation ◽  
Animal Species ◽  
Genetic Material ◽  
Developmental Potential ◽  
In Captivity ◽  
Breeding Programmes ◽  
Sus Scrofa Domesticus

In vitro embryo production strategies have been considered as possible means to protect wild and endangered animal species through assisted breeding programmes. They also offer the possibility to preserve genetic material from such stock or to facilitate breeding in captivity. The relevant technologies, however, have been developed to meet the needs of oocytes and embryos of domesticated animals and their suitability for wild species remains largely unknown. This study investigated the ability of in vitro maturation procedures, designed for oocytes of domestic pigs (Sus scrofa domesticus), to support the development of oocytes from wild boar (Sus scrofa)gilts.

98 VITRIFICATION OF ZYGOTES SUPPORTS FULL-TERM DEVELOPMENT IN RABBITS

2008 ◽  
Vol 20 (1) ◽  
pp. 129
Author(s):  
J. Xu ◽  
J. Zhang ◽  
Y. Chen ◽  
M. Cater ◽  
X. Yang ◽  
...  
Keyword(s):  
Embryo Transfer ◽  
Genetic Material ◽  
Full Term ◽  
Human Reproduction ◽  
Blastocyst Development ◽  
Cold Surface ◽  
Cell Stage ◽  
Disease Study ◽  
The University

Rabbit can serve as an excellent model for human reproduction and relevant disease study. The objective of the study was to develop an effective procedure to preserve the rabbit genome by vitrifying zygotes. Sexually matured New Zealand White rabbits maintained under a 16 h light:8 h dark cycle were superovulated with a regime of two 0.3-mg, two 0.4-mg, and two 0.7-mg injections of FSH with an interval of 12 h between, followed by an injection of 200 IU hCG and mating. Presumptive zygotes were flushed from the oviducts and collected by midventral lapartomy 18 h after hCG injection. One-cell-stage embryos were assigned to pre-equilibration at 38.5�C in HEPES-buffered TCM199 supplemented with 20% FBS + 7.5% ethylene glycol (EG) (v/v) + 7.5% dimethylsulphoxide (DMSO) (v/v) (dehydration medium) for 3 min, and subsequently to 1.0 ml of vitrification medium (TCM199 supplemented with 20% FBS + 20% EG and 20% DMSO), as described by Vajta et al. (1998 Mol. Reprod. Dev. 51, 53–58), at room temperature for 3 min. Five to six embryos per group were then vitrified in a micro-droplet (approximately 1–2 µL) by directly dropping them into a thin layer of liquid nitrogen on the solid surface that generated a super cold surface for vitrification. Vitrified embryos were sequentially warmed, rehydrated in 20% FBS M199 with different concentrations of sucrose, and washed in 20% FBS M199 for 5 min. Warmed embryos were assigned either for further in vitro culture or for embryo transfer to test corresponding developmental potentials. Dutch rabbits were used as recipients in the procedure of asynchronous ovulation induction (22-h delay to zygote donors) by an intramuscular injection of 15 µg of GnRH per doe. Three or four warmed zygotes were surgically transferred into the recipients on the same day of thawing. Pregnancy was monitored by palpation and/or ultrasound on Days 14–16 post-embryo transfer (ET); C-sections were performed on Day 31 to retrieve full-term developed newborns. Preliminary results showed that a 96% (n = 35) post-warming survival rate was achieved with vitrified rabbit zygotes; subsequent cleavage and blastocyst development were 41.6 and 33.3%, respectively. Transfer of a total of 23 warmed embryos into 6 recipients resulted in 5 pregnancies (83.3%, 5/6). Five live kits (21.7%, 5/23) were delivered. Our study suggests that vitrification of rabbit zygotes is a feasible approach for preserving rabbit genetic material. The establishment of suitable conditions for the vitrification of rabbit zygotes could be useful as a model for vitrification of human 1-celled embryos. The authors thank the staff of the animal facility at the University of Connecticut for animal care and maintenance. This work was supported by NIH/NCRR-SBIR grant: 1R43RR020261-01.

scholarly journals Transcriptional profile of bovine preimplantation development selected based on G6PDH activity

2021 ◽  
Vol 5 (1) ◽  
pp. 001-003
Author(s):  
Ghanem Nasser ◽  
Samy Romysa ◽  
Kassab Eman Kh ◽  
Khalil Beshoy SF ◽  
Kordy Aya Ahmed ◽  
...  
Keyword(s):  
Embryonic Development ◽  
Genetic Material ◽  
Implantation Rate ◽  
Short Review ◽  
Oocyte Quality ◽  
Blastocyst Stage ◽  
Blue Staining ◽  
G6pdh Activity ◽  
Cell Stage ◽  
Developmental Potential

The oocyte is the female gamete that contributes not only half of the genetic material but also all of the cytoplasm to the zygote, supplying the transcripts, proteins, mitochondria and other components necessary for early embryonic development. The intrinsic oocyte quality is one of the main factors affecting the embryo yield, the implantation rate and the rate of healthy offspring. It is obvious that a fertilized oocyte must reach the blastocyst stage within 6–9 days in the proper culture conditions to have a significant chance of inducing a pregnancy and producing an offspring. The ability to sustain the first week of embryonic development is clearly influenced by the follicular status from which the oocyte is obtained indicating that this developmental potential is inherent within certain oocytes. Since most early embryos that do not reach the blastocyst stage are blocked at or close to the maternal to zygotic transition (MZT)-stage, which occurs at the eight-cell stage in cattle, one could speculate that incompetent oocytes fail to appropriately activate the embryonic genome. Oocyte selection based on glucose-6-phosphate dehydrogenase (G6PDH) activity has been successfully used to differentiate between competent and incompetent bovine oocytes. Recently, molecular regulation of genes regulating biological process of Brilliant Cresyl Blue staining (BCB) selected oocytes and embryos was investigated to explain their variation in quality and developmental potentiality. This short review will highlights some of these efforts that have been done in this interesting area of research.

251 DEVELOPMENTAL AND BIOENERGY/OXIDATIVE CHARACTERIZATION OF PREPUBERTAL OVINE OOCYTES MATURED IN VITRO

2013 ◽  
Vol 25 (1) ◽  
pp. 273
Author(s):  
N. A. Martino ◽  
R. Russo ◽  
M. Filioli Uranio ◽  
L. Bogliolo ◽  
F. Amati ◽  
...  
Keyword(s):  
Superoxide Dismutase ◽  
Distribution Pattern ◽  
Embryo Transfer ◽  
Embryo Culture ◽  
In Vitro Maturation ◽  
Farm Animals ◽  
Homogeneous Distribution ◽  
Fluorescent Intensity ◽  
Developmental Potential

Juvenile in vitro embryo transfer in farm animals reduces the generation interval and increases the rate of genetic gain. In human reproductive medicine, it enables the preservation of female fertility of young patients affected by cancer or by premature ovarian failure. The developmental competence of in vitro-produced juvenile embryos is strictly related to oocyte quality. The aim of the present study was to analyse the developmental potential and the mitochondrial/oxidative status of ovine prepubertal oocytes matured in vitro to clarify their suitability in juvenile in vitro embryo transfer programs. Oocytes from the ovaries of slaughtered prepubertal lambs (less than 6 months of age) were analysed after in vitro maturation. After cumulus cell removal, oocytes at the metaphase II stage (MII) underwent either IVF plus in vitro embryo culture (Experiment 1; n = 200; Bogliolo et al. 2011 Reprod. Fert. Dev. 23, 809–817) or confocal analysis of mitochondria (mt) and reactive oxygen species (ROS) fluorescence distribution, intensity, and colocalization (Experiment 2; n = 30; Martino et al. 2012 Fertil. Steril. 97, 720–728) or scavenger enzyme [superoxide dismutase (Ambruosi et al. 2011 PLoS ONE 6, e27452) and catalase (Beers and Sizer 1952 J. Biol. Chem. 195, 133–140)] activity analyses in cell lysates of individual oocytes (Experiment 3; n = 7). In Experiment 1, 150 of 200 MII oocytes (75%) cleaved after 30 h of in vitro embryo culture, and 36 of 150 2- to 4-cell-stage embryos (24%) reached the blastocyst stage at Day 8. In Experiment 2, 60 of 111 (54%) oocytes selected for in vitro maturation culture reached the MII stage, and 30 of them (50%) with a regular size (>150 µm in diameter) and morphology were analysed for bioenergy/redox parameters. Fourteen of 30 oocytes (47%) showed a heterogeneous (perinuclear, pericortical, or both) mt distribution pattern, and the remaining 16 of 30 oocytes (53%) showed a homogeneous distribution of small mt aggregates. Intracellular ROS were uniformly distributed, thus not corresponding to the mt distribution pattern. Fluorescent intensity of mt and ROS labelling, expressed as arbitrary densitometric units, were 821.4 ± 274.7 and 737.6 ± 226.5 in oocytes with a heterogeneous pattern and 723.7 ± 371.6 and 831.7 ± 263.7 in oocytes with a homogeneous pattern, respectively (not significant). The mt/ROS colocalization (Pearson correlation coefficient) did not differ between heterogeneous (0.47 ± 0.2) and homogeneous (0.51 ± 0.09; not significant) oocytes. In Experiment 3, superoxide dismutase (n = 4) and catalase activity (n = 3) values were 1.09 ± 0.03 and 10.63 ± 1.96 IU mg–1 of protein, respectively. This study provides basal values of bioenergy/redox parameters in prepubertal lamb MII oocytes as related to their developmental potential and may increase the knowledge of prepubertal oocyte physiology compared with their young adult counterparts.

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