Gene expression and metabolic response of bovine oviduct epithelial cells to the early embryo

During its journey through the oviduct, the bovine embryo may induce transcriptomic and metabolic responses, via direct or indirect contact, from bovine oviduct epithelial cells (BOECs). An in vitro model using polyester mesh was established, allowing the study of the local contact during 48 h between a BOEC monolayer and early embryos (2- or 8-cell stage) or their respective conditioned media (CM). The transcriptomic response of BOEC to early embryos was assessed by analyzing the transcript abundance of SMAD6, TDGF1, ROCK1, ROCK2, SOCS3, PRELP and AGR3 selected from previous in vivo studies and GPX4, NFE2L2, SCN9A, EPSTI1 and IGFBP3 selected from in vitro studies. Moreover, metabolic analyses were performed on the media obtained from the co-culture. Results revealed that presence of early embryos or their CM altered the BOEC expression of NFE2L2, GPX4, SMAD6, IGFBP3, ROCK2 and SCN9A. However, the response of BOEC to two-cell embryos or their CM was different from that observed to eight-cell embryos or their CM. Analysis of energy substrates and amino acids revealed that BOEC metabolism was not affected by the presence of early embryos or by their CM. Interestingly, embryo metabolism before embryo genome activation (EGA) seems to be independent of exogenous sources of energy. In conclusion, this study confirms that early embryos affect BOEC transcriptome and BOEC response was embryo stage specific. Moreover, embryo affects BOEC via a direct contact or via its secretions. However transcriptomic response of BOEC to the embryo did not manifest as an observable metabolic response.

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115 In Vivo Transcriptomic Response of Bovine Oviduct Epithelial Cells to the Early Embryo

Reproduction Fertility and Development ◽

10.1071/rdv30n1ab115 ◽

2018 ◽

Vol 30 (1) ◽

pp. 197

Author(s):

B. Rodríguez-Alonso ◽

M. Hamdi ◽

J. M. Sánchez ◽

A. Gutierrez-Adán ◽

P. Lonergan ◽

...

Keyword(s):

Epithelial Cells ◽

Housekeeping Genes ◽

Local Effect ◽

Early Embryo ◽

Cell Stage ◽

Transcriptomic Response ◽

Precise Position ◽

Horizon 2020 ◽

Proximal Site

The presence of a single 8-cell embryo does not alter the transcriptome of the cells of the oviducal isthmus, although a local effect at the precise position of the embryo cannot be ruled out. Thus, we aimed to study the local embryo effect on the transcriptomic response of the epithelial cells of the oviduct in vivo. Fifteen heifers were synchronized and all showed standing heat and were artificially inseminated. All heifers were slaughtered on Day 2.5 after oestrus. The oviducts from 13 animals (with a corpus luteum, CL) were isolated, trimmed free of tissue and divided between ampulla and isthmus. The ipsilateral isthmus was then divided into smaller sections (2 cm). Each section was sequentially flushed until the embryo was located and was then opened and scraped longitudinally to obtain the epithelial cells. Cells were snap-frozen in LN2 for gene expression analysis. All recovered embryos were found at the beginning of the isthmus of the oviduct ipsilateral to the CL. Three at 2-cell stage and 1 at 8-cell stage. The recovery rate was 30.8% (4/13) and only samples from these 4 animals were used for analysis. The 2-cm sections selected for the transcriptomic analysis were embryo section (ES), in which the embryo was found; proximal section (PS), through which the embryo had passed; distal section (DS), on the uterine side of the embryo; and contralateral section (CS), section from the contralateral isthmus. The expression pattern of 10 differentially expressed genes between the isthmus of pregnant and cyclic heifers (Maillo et al. 2015 Biol Reprod. 92, 144) were assessed by RTq-PCR relative to 2 housekeeping genes, H2A.Z and ACTG. Five up-regulated genes (STK32A, SLC26A3, KERA, QRFPR, MCTP1) and 5 down-regulated (SOD3, PRELP, VAT1L, SOCS3, CCL20) were analysed. One-way ANOVA and t-test was used for statistical analysis. Comparison between ES and the CS revealed one significantly altered gene (VAT1L). This is in agreement with our in vivo results in which VAT1L was also down-regulated in the presence of embryos. Comparison within the ipsilateral oviduct of ES and PS samples revealed STK32A, SLC26A3, QRFPR, MCTP1, and SOCS3 transcripts significantly down-regulated compared with DS samples, whereas the expression for CCL20 was different between ES and DS but similar to the PS. In conclusion, the fact that 5 out of 10 transcripts were different between the segment where the embryo was collected and other locations in the oviduct suggests the presence of embryo site-specific signal. However, comparison between the ipsilateral embryo site with the contralateral site revealed that only one transcript was different. Moreover, the similarities in the ipsilateral oviduct between embryo and proximal site may be due to the passage of the embryo. Furthermore, the location of the embryo close to the ampullary-isthmic junction may mask the effect due to the spatial differences of the bovine oviduct. Research supported by EU, Horizon 2020 Marie Sklodowska-Curie, REPBIOTECH 675526; Spanish MINECO AGL2015-70140-R & AGL2015-66145-R; OECD-CoOperative Prog TAD/CRP JA00092482.

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293 EFFECT OF GUAIAZULENE ON IN VITRO BOVINE EMBRYO PRODUCTION

Reproduction Fertility and Development ◽

10.1071/rdv19n1ab293 ◽

2007 ◽

Vol 19 (1) ◽

pp. 262 ◽

Cited By ~ 1

Author(s):

I. Dimitriadis ◽

E. A. Rekka ◽

E. Vainas ◽

G. S. Amiridis ◽

C. A. Rekkas

Keyword(s):

Lipid Peroxidation ◽

Embryo Development ◽

Antioxidant Properties ◽

Thiobarbituric Acid ◽

Early Embryo ◽

Bovine Embryo ◽

Embryo Production ◽

Reactive Material

The substrates used in in vitro embryo production (IVP) mimic the in vivo fluids in which oocytes mature, oocytes are fertilized, and the early embryos develop (follicular and oviductal fluid). It is well established that oxidative stress negatively affects in vitro culture (IVC) outcomes. Guaiazulene (G) is a component of chamomile species oil with known antioxidant properties. In the present study, all IVP media were modified by the addition of G solutions so that the former exhibited a total protection against induced lipid peroxidation (TPaLP) similar to that of the respective in vivo environment. The IVP outcomes were then compared between G-processed and control oocytes. Bovine preovulatory follicular (BF) and oviductal (BO) fluid samples were collected from 10 Holstein 4- to 5-year-old cows in estrus. TPaLP was assessed according to the samples' ability to inhibit rat hepatic microsomal lipid peroxidation, by determination of the 2-thiobarbituric acid reactive material. TPaLP (mean % � SEM) of the BF and BO were 70.63 � 10.03 and 16.33 � 4.33, respectively, whereas those of the IVP [in vitro-matured (IVM), in vitro-fertilized (IVF), and IVC] media were lower (17.94 � 1.66, -1.82 � 0.78, and 14.57 � 1.26, respectively). TPaLP of the 0.1 mM G-modified IVP medium increased to 67.2 � 5.85, 19.98 � 2.49, and 69.19 � 6.22, respectively. A total of 2041 class A oocytes were used. The proportion of cleavage, early embryo development (embryos with more than 4 cells), or both after IVP (18 h IVM–5% CO2 in air, and 18 h IVF, 48 h IVC–5% CO2, 10% O2, 85% N) in the presence of G (n = 1237) during each of the IVP phases or any possible combination of IVP phases was compared with the respective control (C, n = 804). Statistical analysis was performed by a chi-squared test; P < 0.05 was considered significant. G improved cleavage and embryo development rates when present during IVM (79.4 and 57.8% vs. 64.5 and 38.2% for C) or both IVM and IVC (78.0 and 60.7% vs. 57.8 and 36.5%, respectively). When present only during 18 h of IVF, G had no effect on embryo production. However, an increased embryo development rate resulted from the combined exposure to G during IVF and IVM (56.4 vs. 29.6%), during IVF and IVC (55.3 vs. 35.5%), or at all IVP phases (56.6 vs. 34.9%). The latter effect resembled the one obtained after G addition only to the IVC medium (62.5 vs. 39.7%, respectively). We concluded that the addition of G to IVP substrates, at concentrations that mimic the in vivo TPaLP conditions, could promote bovine IVP efficiency.

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Oviductal response to gametes and early embryos in mammals

Reproduction ◽

10.1530/rep-16-0120 ◽

2016 ◽

Vol 152 (4) ◽

pp. R127-R141 ◽

Cited By ~ 34

Author(s):

Veronica Maillo ◽

Maria Jesus Sánchez-Calabuig ◽

Ricaurte Lopera-Vasquez ◽

Meriem Hamdi ◽

Alfonso Gutierrez-Adan ◽

...

Keyword(s):

Embryo Development ◽

Reproductive Tract ◽

Early Embryo ◽

Secretory Cells ◽

Oocyte Fertilization ◽

Early Embryos ◽

Significant Research ◽

Oviductal Fluid

The oviduct is a complex and organized thin tubular structure connecting the ovary with the uterus. It is the site of final sperm capacitation, oocyte fertilization and, in most species, the first 3–4days of early embryo development. The oviductal epithelium is made up of ciliary and secretory cells responsible for the secretion of proteins and other factors which contribute to the formation of the oviductal fluid. Despite significant research, most of the pathways and oviductal factors implicated in the crosstalk between gametes/early embryo and the oviduct remain unknown. Therefore, studying the oviductal environment is crucial to improve our understanding of the regulatory mechanisms controlling fertilization and embryo development. In vitro systems are a valuable tool to study in vivo pathways and mechanisms, particularly those in the oviducts which in livestock species are challenging to access. In studies of gamete and embryo interaction with the reproductive tract, oviductal epithelial cells, oviductal fluid and microvesicles co-cultured with gametes/embryos represent the most appropriate in vitro models to mimic the physiological conditions in vivo.

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Influence of co-culture during maturation on the developmental potential of equine oocytes fertilized by intracytoplasmic sperm injection (ICSI)

Reproduction ◽

10.1530/rep.0.1210925 ◽

2001 ◽

pp. 925-932 ◽

Cited By ~ 55

Author(s):

X Li ◽

LH Morris ◽

WR Allen

Keyword(s):

Epithelial Cells ◽

Intracytoplasmic Sperm Injection ◽

Fibroblast Cells ◽

Cell Stage ◽

Developmental Potential ◽

Fetal Fibroblast ◽

Nuclear Maturation ◽

Fetal Fibroblasts ◽

Oviduct Epithelial Cells

The influence of co-culture with either oviduct epithelial cells or fetal fibroblast cells on in vitro maturation of equine oocytes and their potential for development to blastocysts and fetuses after intracytoplasmic sperm injection (ICSI) was investigated. The oocytes were obtained from ovaries from abattoirs and were matured in vitro for 28-30 h in TCM-199 only, or in TCM-199 co-culture with oviduct epithelial cells or fetal fibroblast cells. Metaphase II oocytes were subjected to ICSI with an ionomycin-treated spermatozoon. The injected oocytes were cultured for 7-9 days in Dulbecco's modified Eagle's medium. Morphologically normal early blastocysts were transferred to the uteri of recipient mares. Nuclear maturation rates and the rates of cleavage to the two-cell stage for injected oocytes were similar in the groups of oocytes that were matured in TCM-199 (49 and 63%), in co-culture with oviduct epithelial cells (53 and 65%) or in co-culture with fetal fibroblasts (51 and 57%). There were no significant differences in the proportions of blastocysts that developed from the two-cell embryos derived from oocytes matured by co-culture with either oviduct epithelial cells (30%) or fetal fibroblasts (17%). However, significantly higher proportions of blastocysts were produced from both these co-culture groups than from the groups of oocytes matured in TCM-199 only (P < 0.05). Six of the blastocysts that had developed from oocytes co-cultured with oviduct epithelial cells were transferred into recipient mares and four pregnancies resulted. These results demonstrate a beneficial influence of co-culture with either oviduct epithelial cells or fetal fibroblasts for maturation of oocytes in vitro.

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Hydrogen peroxide levels in mouse oocytes and early cleavage stage embryos developed in vitro or in vivo

Development ◽

10.1242/dev.109.2.501 ◽

1990 ◽

Vol 109 (2) ◽

pp. 501-507 ◽

Cited By ~ 6

Author(s):

M.H. Nasr-Esfahani ◽

J.R. Aitken ◽

M.H. Johnson

Keyword(s):

Reproductive Tract ◽

Female Reproductive Tract ◽

Cell Stage ◽

Mouse Oocytes ◽

Early Embryos ◽

Individual Mouse ◽

The Relationship ◽

Developmental Block

We describe a fluorimetric method for measuring the level of H2O2 in individual mouse oocytes and early embryos. Levels of H2O2 are low but detectable in unfertilized oocytes recovered freshly from the female reproductive tract. The levels in early cleaving embryos (1-cell to 8-cell stages) immediately after recovery from the female tract seem to be slightly higher the later the stage examined. However, when embryos are cultured in vitro from the 1-cell or early 2-cell stage, H2O2 levels rise when the embryos reach the mid-2-cell stage and remain elevated until they enter the early 4-cell stage. No equivalent elevation of H2O2 is seen during the transition from 1-cell to 2-cell or from 4-cell to 8-cell stages. Embryos that are able to develop successfully in vitro, as well as those that show a developmental block at the 2-cell stage on culture in vitro, both show this rise in H2O2 levels after in vitro culture. The relationship between the rise in H2O2 and the ‘2-cell block’ to development is discussed.

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Identification of a Novel Role for Endothelins within the Oviduct

Endocrinology ◽

10.1210/en.2009-1155 ◽

2010 ◽

Vol 151 (6) ◽

pp. 2858-2867 ◽

Cited By ~ 22

Author(s):

Myoungkun Jeoung ◽

Sungeun Lee ◽

Hee-kyung Hawng ◽

Yong-Pil Cheon ◽

Youn Kyung Jeong ◽

...

Keyword(s):

Epithelial Cells ◽

Embryo Development ◽

Early Embryo ◽

Receptor Subtypes ◽

Early Embryo Development ◽

Vitro Fertilization ◽

Protein Superfamilies ◽

Endothelin 3

Endothelins were first identified as potent vasoactive peptides; however, diversity in the biological function of these hormones is now evident. We have identified a novel role for endothelins: a requirement for these peptides within the oviduct during fertilization and/or early embryo development. In vivo, treatment after ovulation with a dual endothelin receptor antagonist (tezosentan) decreased the number of two-cell embryos that could be collected from within the oviducts. In vitro fertilization experiments showed that gamete viability and their ability to fertilize were not affected by treatment with this antagonist, suggesting that the effect observed in vivo was mediated by the oviduct itself. Expression of mRNA for all three isoforms of the endothelins and both receptor subtypes was detectable within the oviduct. Expression of mRNA for endothelin-3 was regulated by gonadotropins in epithelial cells of the oviduct and increased specifically within the isthmus of this structure. Immunostaining revealed localization of both endothelin receptors A and B to the columnar epithelial cells within the oviduct, suggestive of a local role for endothelins in the regulation of epithelial function and ultimately oviductal secretions. A microarray analysis revealed three likely endothelin-regulated protein networks for future analysis: the TGFβ, IL-10, and CCAAT/enhancer-binding protein superfamilies. Overall, these results suggest a novel and requisite role for endothelins within the oviduct during fertilization and/or early embryo development.

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83 BONE MORPHOGENETIC PROTEIN SIGNALING DURING INTERACTION OF THE BOVINE EMBRYO WITH OVIDUCTAL EPITHELIAL CELLS IN VITRO

Reproduction Fertility and Development ◽

10.1071/rdv29n1ab83 ◽

2017 ◽

Vol 29 (1) ◽

pp. 149

Author(s):

E. V. García ◽

M. Hamdi ◽

A. D. Barrera ◽

M. J. Sánchez-Calabuig ◽

A. Gutiérrez-Adán ◽

...

Keyword(s):

Epithelial Cells ◽

Mrna Expression ◽

Relative Abundance ◽

Bovine Embryo ◽

Cell Stage ◽

Expression Levels ◽

Bmp Receptors ◽

Bmp Signalling ◽

Mrna Expression Levels

In previous studies, we have demonstrated that different signalling components of bone morphogenetic proteins (BMP) are expressed in an anatomically and temporally regulated fashion in the bovine oviduct. However, a local response of this signalling to the embryo presence has not been elucidated yet. The aim of the present study was to evaluate whether the interaction of the embryo with the oviduct can induce changes in the gene expression of BMP signalling components. For this purpose, we used an in vitro co-culture system of a bovine oviducal epithelial cell (BOEC) monolayer with pre-implantation embryos in 2 developmental time points: before and during the main phase of embryonic genome activation (EGA). Isthmus epithelial cells from post-ovulatory stage oviducts (Day 2–4) were cultured in 500 μL of SOF + 10% FCS in 4-well plates at 38.5°C, 5% CO2, 5% O2, and 90% N2. On Day 6 of culture, medium was replaced with SOF + 5% FCS, and 24 h later BOEC monolayer was cultured in the absence or presence of in vitro-produced embryos from 2- to 8-cell stage [G1 BOEC; 33–54 h post-insemination (hpi)] or from 8- to 16-cell stage (G2 BOEC; 54–98 hpi) in the same conditions. In both groups, a polyester mesh was used to define a local co-culture area, and 30 embryos per well were placed in a 6 × 5 grid over the monolayer. In addition, as control groups, embryos in both developmental stages were cultured either in SOF + 5% FCS (G1 FCS and G2 FCS) or in SOF + 3 mg mL−1 BSA (G1 BSA and G2 BSA). At 54 hpi (G1 BOEC/BSA/FCS) or 98 hpi (G2 BOEC/BSA/FCS), embryos that reached 8- or 16-cell stage, respectively, were transferred to SOF + BSA and cultured until Day 9. The mRNA expression levels of 3 BMP receptors (BMPRIA/IB/II), 2 signalling proteins (SMAD1/5), 1 inhibitor (SMAD6), and 1 target gene (ID2) were analysed by qPCR in 5 samples of BOEC cultured with or without embryos before or during EGA, and in 3 pools of 10 embryos at 8 (54 hpi), 16 (98 hpi), and blastocyst stage (Day 7–8) from all groups. Genes H2A.Z and ACTG1 were used as housekeeping genes, and statistical differences were assessed by ANOVA. The presence of the embryo, irrespective the stage, significantly reduced the expression levels of BMPRIB, BMPRII, SMAD1, SMAD6, and ID2 in BOEC. Embryos that interacted with BOEC before EGA (G1 BOEC) showed a significant increase in the relative abundance of SMAD1 at the 8-cell stage compared with controls. Moreover, embryos that interacted with BOEC during EGA (G2 BOEC) showed a significant increase in the relative abundance of BMPRIB, BMPRII, and ID2 at the 16-cell stage when compared with controls. However, no differences were observed in the mRNA expression levels of BMP signalling components in the blastocysts between groups. In conclusion, local embryo-oviduct interaction in vitro induces changes in the transcriptional levels of BMP signalling, causing a bidirectional response that reduces the expression levels of this signalling in the oviducal cells while increases them in the embryo at early stages. This suggests that BMP signalling pathway could be involved in an early cross-talk between the bovine embryo and the oviduct during first stages of development.

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Nobiletin-induced partial abrogation of deleterious effects of AKT inhibition on preimplantation bovine embryo development in vitro

Biology of Reproduction ◽

10.1093/biolre/ioab184 ◽

2021 ◽

Author(s):

Yulia N Cajas ◽

Karina Cañón-Beltrán ◽

Carolina Núñez-Puente ◽

Alfonso Gutierrez-Adán ◽

Encina M González ◽

...

Keyword(s):

Embryo Development ◽

Culture Media ◽

Cell Number ◽

Early Embryo ◽

Bovine Embryo ◽

Cell Stage ◽

Developmental Effect ◽

Promote Cell Survival ◽

Development In Vitro

Abstract During preimplantational embryo development, PI3K/AKT regulates cell proliferation and differentiation and nobiletin modulates this pathway to promote cell survival. Therefore, we aimed to establish whether, when the AKT cascade is inhibited using inhibitors III and IV, nobiletin supplementation to in vitro culture media during the minor (2 to 8-cell stage, MNEGA) or major (8 to 16-cell stage, MJEGA) phases of EGA is able to modulate the development and quality of bovine embryos. In vitro zygotes were cultured during MNEGA or MJEGA phase in SOF + 5% FCS or supplemented with: 15 μM AKT-InhIII; 10 μM AKT-InhIV; 10 μM nobiletin; nobiletin+AKT-InhIII; nobiletin+AKT-InhIV; 0.03% DMSO. Embryo development was lower in treatments with AKT inhibitors, while combination of nobiletin with AKT inhibitors was able to recover their adverse developmental effect and also increase blastocyst cell number. The mRNA abundance of GPX1, NFE2L2, and POU5F1 was partially increased in 8- and 16-cell embryos from nobiletin with AKT inhibitors. Besides, nobiletin increased the p-rpS6 level whether or not AKT inhibitors were present. In conclusion, nobiletin promotes bovine embryo development and quality and partially recovers the adverse developmental effect of AKT inhibitors which infers that nobiletin probably uses another signalling cascade that PI3K/AKT during early embryo development in bovine.

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Bovine embryo-oviduct interaction in vitro reveals an early cross talk mediated by BMP signaling

Reproduction ◽

10.1530/rep-16-0654 ◽

2017 ◽

Vol 153 (5) ◽

pp. 631-643 ◽

Cited By ~ 13

Author(s):

Elina V García ◽

Meriem Hamdi ◽

Antonio D Barrera ◽

María J Sánchez-Calabuig ◽

Alfonso Gutiérrez-Adán ◽

...

Keyword(s):

Bone Morphogenetic Proteins ◽

Relative Abundance ◽

Cross Talk ◽

Early Embryo ◽

Bmp Signaling ◽

Bovine Embryo ◽

Cell Stage ◽

Embryonic Genome ◽

Signaling Components

Signaling components of bone morphogenetic proteins (BMPs) are expressed in an anatomically and temporally regulated fashion in bovine oviduct. However, a local response of this signaling to the presence of the embryo has yet to be elucidated. The aim of the present study was to evaluate if early embryo-oviduct interaction induces changes in the gene expression of BMP signaling components. For this purpose, we used an in vitro co-culture system to investigate the local interaction between bovine oviductal epithelial cells (BOEC) from the isthmus region with early embryos during two developmental periods: before (from the 2-cell to 8-cell stage) or during (from the 8-cell to 16-cell stage) the main phase of embryonic genome activation (EGA). Exposure to embryos, irrespective of the period, significantly reduced the relative abundance of BMPR1B, BMPR2, SMAD1, SMAD6 and ID2 mRNAs in BOEC. In contrast, embryos that interacted with BOEC before EGA showed a significant increase in the relative abundance of SMAD1 mRNA at the 8-cell stage compared to embryos cultured without BOEC. Moreover, embryos at the 16-cell stage that interacted with BOEC during EGA showed a significant increase in BMPR1B, BMPR2 and ID2 mRNA. These results demonstrate that embryo-oviduct interaction in vitro induces specific changes in the transcriptional levels of BMP signaling, causing a bidirectional response that reduces the expression levels of this signaling in the oviductal cells while increases them in the early embryo. This suggests that BMP signaling pathway could be involved in an early cross talk between the bovine embryo and the oviduct during the first stages of development.

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145 CHANGES IN OXYGEN COMSUMPTION RATES OF EMBRYOS IN KOREAN CATTLE

Reproduction Fertility and Development ◽

10.1071/rdv22n1ab145 ◽

2010 ◽

Vol 22 (1) ◽

pp. 231

Author(s):

C. Y. Choe ◽

S. R. Cho ◽

J. K. Son ◽

S. H. Choi ◽

C. Y. Cho ◽

...

Keyword(s):

Oxygen Consumption ◽

Embryo Quality ◽

Blastocyst Stage ◽

Bovine Embryo ◽

Bovine Embryos ◽

Cell Stage ◽

Significant Difference ◽

Morula Stage

Oxygen consumption has been regarded as a useful indicator for assessment of mammalian embryo quality. This study was carried out to identify whether oxygen consumption rates measured in bovine embryos using SECM can be used as a standard criteria to evaluate bovine embryo quality. Oxygen consumption of bovine embryos at various developmental stages was measured and analyzed using SECM and ANOVA analysis, respectively. We found that the oxygen consumption significantly increased in blastocyst-stage embryos compared to other stage embryos (from 2-cell stage to morula stage), indicating that oxygen consumption reflects the cell number (5.2-7.6 × 1014 mol-1 s-1 v. 1.2-2.4 × 1014 mol-1 s-1, P < 0.05). There was no significant difference between 2-cell-stage embryos and 8-cell-stage embryos. In the morula-stage embryos, the oxygen consumption of in vivo derived embryos was significantly higher than that of in vitro produced embryos (4.0 × 1014 mol-1 s-1 v. 2.4 × 1014 mol-1 s-1, P < 0.05). However, there was no significant difference in consumption of oxygen by in vivo and in vitro derived bovine blastocyst-stage embryos (P > 0.05). Good-quality embryos with grade 1 or 2 showed significantly higher oxygen consumption than grade 3 or 4 embryos. These results showed that SECM could measure oxygen consumption in bovine embryos and the oxygen consumption could reflect embryonic development stage and embryo quality.

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