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David K Gardner - One of the best experts on this subject based on the ideXlab platform.
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impact of the ivf laboratory environment on human Preimplantation Embryo phenotype
Journal of Developmental Origins of Health and Disease, 2017Co-Authors: David K Gardner, Rebecca L KelleyAbstract:The phenotype of the human Embryo conceived through in vitro fertilization (IVF), that is its morphology, developmental kinetics, physiology and metabolism, can be affected by numerous components of the laboratory and Embryo culture system (which comprise the laboratory environment). The culture media formulation is important in determining Embryo phenotype, but this exists within a culture system that includes oxygen, temperature, pH and whether an Embryo is cultured individually or in a group, all of which can influence Embryo development. Significantly, exposure of an Embryo to one suboptimal component of the culture system of laboratory typically predisposes the Embryo to become more vulnerable to a second stressor, as has been well documented for atmospheric oxygen and individual culture, as well as for oxygen and ammonium. Furthermore, the inherent viability of the human Embryo is derived from the quality of the gametes from which it is created. Patient age, aetiology, genetics, lifestyle (as well as ovarian stimulation in women) are all known to affect the developmental potential of gametes and hence the Embryo. Thus, as well as considering the impact of the IVF laboratory environment, one needs to be aware of the status of the infertile couple, as this impacts how their gametes and Embryos will respond to an in vitro environment. Although far from straight forward, analysing the interactions that exist between the human Embryo and its environment will facilitate the creation of more effective and safer treatments for the infertile couple.
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antioxidants improve mouse Preimplantation Embryo development and viability
Human Reproduction, 2016Co-Authors: Thi T Truong, Yu May Soh, David K GardnerAbstract:STUDY QUESTION What is the effect of three antioxidants (acetyl-L-carnitine, N-acetyl-L-cysteine and α-lipoic acid), when used individually and in combination, on mouse Embryo development in culture, and subsequent fetal development post-transfer? SUMMARY ANSWER A combination of antioxidants resulted in significant increases in blastocyst cell number, maintained intracellular glutathione (GSH) levels, supported earlier cleavage times from 5-cell stage to expanded blastocyst, and improved fetal developmental irrespective of incubator oxygen concentration. WHAT IS KNOWN ALREADY Acetyl-L-carnitine, N-acetyl-L-cysteine and α-lipoic acid have been shown to have beneficial effects individually in several tissues, and most recently on developing Embryos, in the presence of oxidative stress. STUDY DESIGN, SIZE, DURATION Morphokinetics of mouse Embryos were quantitated using time-lapse imaging. GSH levels in pronucleate oocytes were measured. Blastocysts underwent differential nuclear staining for inner cell mass and trophectoderm cells or were transferred to recipient females to assess implantation and fetal development. PARTICIPANTS/MATERIALS, SETTINGS, METHODS Pronucleate oocytes from F1 mice were cultured in 5 or 20% oxygen either individually or in groups of 10, in media G1/G2, in the presence or absence of 10 µM acetyl-L-carnitine /10 µM N-acetyl-L-cysteine /5 µM α-lipoic acid, either individually or in combination. Controls were Embryos cultured without antioxidants. Intracellular levels of reduced glutathione were quantitated in pronucleate oocytes. Embryo development and viability were analysed through time-lapse microscopy and Embryo transfers. MAIN RESULTS AND THE ROLE OF CHANCE Antioxidants significantly increased mouse blastocyst cell numbers compared with control when used individually (P< 0.05) and to a greater effect when all three were used in combination (P< 0.01) in 20% oxygen. The combination of antioxidants resulted in faster development rates to 5-cell cleavage stage, which continued until the expanded blastocyst stage when cultured in 20% oxygen. The beneficial effects of combining the antioxidants were greater for Embryos cultured individually as opposed to in groups of 10 and for those Embryos cultured in 20% compared to 5% oxygen. Levels of GSH were significantly decreased in control Embryos that were incubated in the absence of antioxidants in 20% oxygen (P< 0.01), compared with in vivo flushed Embryos. However, when Embryos were cultured with antioxidants the level of GSH was not different to that of in vivo developed Embryos. Embryos cultured in the presence of antioxidants in 20% oxygen and transferred resulted in significantly longer crown-rump length (11.6 ± 0.1 mm versus 11.3 ± 0.1 mm; P< 0.01), heavier fetuses (209.8 ± 11.8 mg versus 183.9 ± 5.9 mg; P< 0.05) and heavier placentas (103.5 ± 3.1 mg versus 93.6 ± 2.7 mg; P< 0.01) compared with controls (all data are mean ± SEM). Further, a post-implantation benefit of the antioxidant combination was also evident after culture in 5% oxygen. LIMITATIONS, REASONS FOR CAUTION Embryo development and implantation was only examined in the mouse. WIDER IMPLICATIONS OF THE FINDINGS These findings show that a combination of antioxidants in the culture media has a highly beneficial effect on mouse Preimplantation Embryo development in vitro and on subsequent fetal development post-transfer. These data indicate a potential role for the inclusion of specific antioxidant combinations in human Embryo culture media irrespective of oxygen concentration. However, before application to human Embryos, a proper evaluation of this approach in prospective, preferably randomized, trials will be required. STUDY FUNDING/COMPETING INTERESTS This work was funded by a research grant from Vitrolife AB (Sweden). The authors have no conflict of interest to declare.
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diagnosis of human Preimplantation Embryo viability
Human Reproduction Update, 2015Co-Authors: David K Gardner, Carmen Rubio, Marcos Meseguer, Nathan R TreffAbstract:background: Transfer of more than a single Embryo in an IVF cycle comes with the finite possibility of a multiple gestation. Even a twin pregnancy confers significant risk to both mother and babies. The move to single-Embryo transfer for all patients will be greatly facilitated by the ability to quantify Embryo viability. Developments in time-lapse incubation systems have provided new insights into the developmental kinetics of the human Preimplantation Embryo. Advances in molecular methods of chromosomal analysis have created platforms for highly effective screening of biopsied Embryos, while noninvasive analysis of Embryo physiology reveals more about the Embryo than can be determined by morphology alone. methods: Recent developments in time-lapse microscopy, molecular karyotyping and in proteomics and metabolomics have been assessed and presented here in a descriptive review. results and conclusions: New algorithms are being created for Embryo selection based on their developmental kinetics in culture, and the impact of factors such as patient etiology and treatment are being clarified. Potential links between morphokinetic data and Embryo kar- yotype are being elucidated. The introduction of new molecular methods of determining Embryo chromosomal complement is proving to be accurate and reproducible, with the future trending toward CGH arrays or next generation sequencing as a rapid and reliable means of analysis, that should be suitable for each IVF clinic to adopt. A relationship between Embryo metabolism and viability is established and is now being con- sidered together with morphokinetic data to create more robust algorithms for Embryo selection. Microfluidic devices have the capacity and po- tential to be used in human IVF clinics for the routine diagnosis of Embryo biomarkers.
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soluble ligands and their receptors in human Embryo development and implantation
Endocrine Reviews, 2015Co-Authors: George Anthony Thouas, Carlos Simon, Francisco Dominguez, Mark P Green, Felipe Vilella, David K GardnerAbstract:Extensive evidence suggests that soluble ligands and their receptors mediate human Preimplantation Embryo development and implantation. Progress in this complex area has been ongoing since the 1980s, with an ever-increasing list of candidates. This article specifically reviews evidence of soluble ligands and their receptors in the human Preimplantation stage Embryo and female reproductive tract. The focus will be on candidates produced by the human Preimplantation Embryo and those eliciting developmental responses in vitro, as well as endometrial factors related to implantation and receptivity. Pathways to clinical translation, including innovative diagnostics and other technologies, are also highlighted, drawing from this collective evidence toward facilitating joint improvements in Embryo quality and endometrial receptivity. This strategy could not only benefit clinical outcomes in reproductive medicine but also provide broader insights into the peri-implantation period of human development to improve f...
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soluble ligands and their receptors in human Embryo development and implantation
Endocrine Reviews, 2015Co-Authors: George Anthony Thouas, Carlos Simon, Francisco Dominguez, Mark P Green, Felipe Vilella, David K GardnerAbstract:Extensive evidence suggests that soluble ligands and their receptors mediate human Preimplantation Embryo development and implantation. Progress in this complex area has been ongoing since the 1980s, with an ever-increasing list of candidates. This article specifically reviews evidence of soluble ligands and their receptors in the human Preimplantation stage Embryo and female reproductive tract. The focus will be on candidates produced by the human Preimplantation Embryo and those eliciting developmental responses in vitro, as well as endometrial factors related to implantation and receptivity. Pathways to clinical translation, including innovative diagnostics and other technologies, are also highlighted, drawing from this collective evidence toward facilitating joint improvements in Embryo quality and endometrial receptivity. This strategy could not only benefit clinical outcomes in reproductive medicine but also provide broader insights into the peri-implantation period of human development to improve fetal and neonatal health.
H J Leese - One of the best experts on this subject based on the ideXlab platform.
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metabolism of the Preimplantation Embryo 40 years on
Reproduction, 2012Co-Authors: H J LeeseAbstract:This review considers how our understanding of Preimplantation Embryo metabolism has progressed since the pioneering work on this topic in the late 1960s and early 1970s. Research has been stimulated by a desire to understand how metabolic events contribute to the development of the zygote into the blastocyst, the need for biomarkers of Embryo health with which to improve the success of assisted conception technologies, and latterly by the 'Developmental Origins of Health and Disease' (DOHaD) concept. However, arguably, progress has not been as great as it might have been due to methodological difficulties in working with tiny amounts of tissue and the low priority assigned to fundamental research on fertility and infertility, with developments driven more by technical than scientific advances. Nevertheless, considerable progress has been made in defining the roles of the traditional nutrients: pyruvate, glucose, lactate, and amino acids; originally considered as energy sources and biosynthetic precursors, but now recognized as having multiple, overlapping functions. Other nutrients; notably lipids, are beginning to attract the attention they deserve. The pivotal role of mitochondria in early Embryo development and the DOHaD concept, and in providing a cellular focus for metabolic events is now recognized. Some unifying ideas are discussed; namely 'stress-response models' and the 'quiet Embryo hypothesis'; the latter aiming to relate the metabolism of individual Preimplantation Embryos to their subsequent viability. The review concludes by updating the state of knowledge of Preimplantation Embryo metabolism in the early 1970s and listing some future research questions.
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amino acid depletion and appearance during porcine Preimplantation Embryo development in vitro
Reproduction, 2005Co-Authors: Paul J Booth, Peter G Humpherson, Terry J Watson, H J LeeseAbstract:Preimplantation Embryos can consume and produce amino acids in a manner dependent upon the stage of development that may be predictive of subsequent viability. In order to examine these relationships in the pig, patterns of net depletion and appearance of amino acids by in vitro produced porcine Preimplantation Embryos were examined. Cumulus oocyte complexes derived from slaughterhouse pre-pubertal pig ovaries were matured for 40h in defined TCM-199 medium (containing PVA) before being fertilised (Day 0) with frozen-thawed semen in Tris‐based medium. After 6h, presumptive zygotes were denuded and cultured in groups of 20, in NCSU-23 medium modified to contain 0.1mM glutamine plus a mixture of 19 amino acids (aa) at low concentrations (0.02‐0.11mM) (NCSU-23aa). Groups of 2‐20 Embryos were removed (dependent on stage) on Day 0 (1 cell), Day 1 (two- and four-cells), Day 4 (compact morulae) and Day 6 (blastocysts) and placed in 4ml NCSU-23aa for 24h. After incubation, the Embryos were removed and the spent media was analysed by HPLC. The net rate of amino acid depletion or appearance varied according to amino acid (P < 0.001) and, apart from serine and histidine, stage of development (P < 0.014). Glycine, isoleucine, valine, phenylalanine, tryptophan, methionine, asparagine, lysine, glutamate and aspartate consistently appeared, whereas threonine, glutamine and arginine were consistently depleted. Five types of stagedependent trends could be observed: Type I: amino acids having high rates of net appearance on Day 0 that reached a nadir on Day 1 or 4 but subsequently increased by Day 6 (glycine, glutamate); Type II: those that exhibited lower rates of net appearance on Days 0 and 6 compared with the intermediate Days 1 and 4 (isoleucine, valine, phenylalanine, methionine, arginine); Type III: amino acids which showed a continuous fall in net appearance (asparagine, aspartate); Type IV: those that exhibited a steady fall in net depletion from Day 0 to Day 6 (glutamine, threonine); Type V: those following no discernable trend. Analysis of further Embryo types indicated that presumptive polyspermic Embryos on Day 0 had increased (P < 0.05) net rates of leucine, isoleucine, valine and glutamate appearance, and reduced (P < 0.05) net rates of threonine and glutamine depletion compared with normally inseminated oocytes. These data suggest that the net rates of depletion and uptake of amino acids by pig Embryos vary between a) amino acids, b) the day of Embryo development and, c) the type of Embryos present at a given stage of development. The results also suggested that the net depletion and appearance rates of amino acids by early pig Embryos might be more similar to those of the human than those of the mouse and cow. Reproduction (2005) 130 655–668
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protection against reactive oxygen species during mouse Preimplantation Embryo development role of edta oxygen tension catalase superoxide dismutase and pyruvate
Molecular Reproduction and Development, 2001Co-Authors: Nicolas M Orsi, H J LeeseAbstract:Oxidative damage due to the production of reactive oxygen species (ROS) is one of a number of culture-induced stresses which may compromise Preimplantation Embryo development in vitro. Ethylenediaminetetraacetic acid (EDTA), reduced oxygen tension, superoxide dismutase (SOD) and catalase (CAT) offer protection against oxidative stress, but few attempts have been made to determine which of these agents, or which combination, is the most effective. In particular, no systematic investigation of their actions and interactions has been made using a multifactorial experimental design. Murine zygotes were cultured in the presence or absence of 10 miccroM EDTA, SOD (100-7,000 U/ml) and CAT (50-100 U/ml) at atmospheric (20%) and reduced (5%) oxygen tensions. Blastocyst formation and hatching rates (at various time points), and cell numbers were recorded, whilst parallel groups of Embryos had their consumption of pyruvate, a hydrogen peroxide scavenger, measured. All parameters interacted significantly and affected blastocyst formation, hatching rate and cell numbers but the effect of EDTA was the most pronounced. There were beneficial effects of 5% O2, CAT and SOD, while 20% O2 had a deleterious effect on development. EDTA improved blastocyst formation and hatching rates but paradoxically led to a reduction in cell number. 5% O2 was the next most significant parameter to enhance Embryo development and also increased cell numbers. No differences in pyruvate uptake were apparent between the various treatment groups. The results suggest that Embryo culture in EDTA-free medium under 5% O2 provides the most practical and physiological conditions for in vitro murine Embryo culture.
George Anthony Thouas - One of the best experts on this subject based on the ideXlab platform.
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soluble ligands and their receptors in human Embryo development and implantation
Endocrine Reviews, 2015Co-Authors: George Anthony Thouas, Carlos Simon, Francisco Dominguez, Mark P Green, Felipe Vilella, David K GardnerAbstract:Extensive evidence suggests that soluble ligands and their receptors mediate human Preimplantation Embryo development and implantation. Progress in this complex area has been ongoing since the 1980s, with an ever-increasing list of candidates. This article specifically reviews evidence of soluble ligands and their receptors in the human Preimplantation stage Embryo and female reproductive tract. The focus will be on candidates produced by the human Preimplantation Embryo and those eliciting developmental responses in vitro, as well as endometrial factors related to implantation and receptivity. Pathways to clinical translation, including innovative diagnostics and other technologies, are also highlighted, drawing from this collective evidence toward facilitating joint improvements in Embryo quality and endometrial receptivity. This strategy could not only benefit clinical outcomes in reproductive medicine but also provide broader insights into the peri-implantation period of human development to improve fetal and neonatal health.
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soluble ligands and their receptors in human Embryo development and implantation
Endocrine Reviews, 2015Co-Authors: George Anthony Thouas, Carlos Simon, Francisco Dominguez, Mark P Green, Felipe Vilella, David K GardnerAbstract:Extensive evidence suggests that soluble ligands and their receptors mediate human Preimplantation Embryo development and implantation. Progress in this complex area has been ongoing since the 1980s, with an ever-increasing list of candidates. This article specifically reviews evidence of soluble ligands and their receptors in the human Preimplantation stage Embryo and female reproductive tract. The focus will be on candidates produced by the human Preimplantation Embryo and those eliciting developmental responses in vitro, as well as endometrial factors related to implantation and receptivity. Pathways to clinical translation, including innovative diagnostics and other technologies, are also highlighted, drawing from this collective evidence toward facilitating joint improvements in Embryo quality and endometrial receptivity. This strategy could not only benefit clinical outcomes in reproductive medicine but also provide broader insights into the peri-implantation period of human development to improve f...
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sex related physiology of the Preimplantation Embryo
Molecular Human Reproduction, 2010Co-Authors: David K Gardner, Mark G Larman, George Anthony ThouasAbstract:Male and female Preimplantation mammalian Embryos differ not only in their chromosomal complement, but in their proteome and subsequent metabolome. This phenomenon is due to a finite period during Preimplantation development when both X chromosomes are active, between Embryonic genome activation and X chromosome inactivation, around the blastocyst stage. Consequently, prior to implantation male and female Embryos exhibit differences in their cellular phenotype. Manifestations of such differences include altered total activity of specific X-linked enzymes and the metabolic pathways they regulate. Subsequently, one would expect to be able to determine differences in the rate of consumption and utilization of specific nutrients between male and female Embryos. Data to date on animal models support this, with sex-specific differences in glucose and amino acid utilization being reported for the mouse and cow blastocysts. Such differences in metabolic phenotype may logically be involved in the reported differences in growth rates between Preimplantation Embryos of different sex. As the fields of proteomics and metabolomics are being increasingly applied to human assisted conception it is prudent to consider how such technologies may be applied to identify sex differences in the human Embryo. Such data would have implications far beyond current invasive technologies used to identify the sex of an Embryo conceived in vitro for the diagnosis of X-linked diseases.
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mitochondrial dysfunction in mouse oocytes results in Preimplantation Embryo arrest in vitro
Biology of Reproduction, 2004Co-Authors: George Anthony Thouas, Alan O Trounson, Ernst J Wolvetang, Gayle M JonesAbstract:Oocyte mitochondrial dysfunction has been proposed as a cause of high levels of developmental retardation and arrest that occur in human Preimplantation Embryos generated using assisted reproductive technology in the treatment of some causes of female infertility. To investigate this, a model of mitochondrial dysfunction was developed in mouse oocytes using a method of photosensitization of the mitochondrion-specific dye, rhodamine-123. After in vitro fertilization, dye-loaded and photosensitized oocytes showed developmental arrest in proportion to irradiation time. Morphological and metabolic assessments of zygotes indicated an increase in mitochondrial permeability that subsequently resulted in apoptotic degeneration. Development was partially restored by inhibition of mitochondrial permeability transition pore formation by oocyte pretreatment with cyclosporin A. Oocyte mitochondria are therefore physiological regulators of early Embryo development and potential sites of pathological insult that may perturb oocyte and subsequent Preimplantation Embryo viability. These findings have important implications for the treatment of clinically infertile women using assisted reproductive technologies.
Andrea Jurisicova - One of the best experts on this subject based on the ideXlab platform.
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the mammalian Embryo s first agenda making trophectoderm
The International Journal of Developmental Biology, 2019Co-Authors: Eszter Posfai, Isidora Rovic, Andrea JurisicovaAbstract:One of the bottlenecks for a successful pregnancy in mammalian species is the implantation of the early Embryo into the wall of the mother’s uterus. The first cell lineage the Embryo sets aside following fertilization is the trophectoderm – a specialized cell type that establishes contact with the mother and mediates Embryo implantation. We summarize the events that lead to the formation of the trophectoderm lineage in the Preimplantation Embryo and highlight key features of this cell type, which could be useful in the clinical setting for prediction of implantation outcomes.
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deadly decisions the role of genes regulating programmed cell death in human Preimplantation Embryo development
Reproduction, 2004Co-Authors: Andrea Jurisicova, Beth M ActonAbstract:Human Preimplantation Embryo development is prone to high rates of early Embryo wastage, particularly under current in vitro culture conditions. There are many possible underlying causes for Embryo demise, including DNA damage, poor Embryo metabolism and the effect of suboptimal culture media, all of which could result in an imbalance in gene expression and the failed execution of basic Embryonic decisions. In view of the complex interactions involved in Embryo development, a thorough understanding of these parameters is essential to improving Embryo quality. An increasing body of evidence indicates that cell fate (i.e. survival/differentiation or death) is determined by the outcome of specific intracellular interactions between pro- and anti-apoptotic proteins, many of which are expressed during oocyte and Preimplantation Embryo development. The recent availability of mutant mice lacking expression of various genes involved in the regulation of cell survival has enabled rapid progress towards identifying those molecules that are functionally important for normal oocyte and Preimplantation Embryo development. In this review we will discuss the current understanding of the regulation of cell death gene expression during Preimplantation Embryo development, with a focus on human Embryology and a discussion of animal models where appropriate.
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expression and regulation of genes associated with cell death during murine Preimplantation Embryo development
Molecular Reproduction and Development, 1998Co-Authors: Andrea Jurisicova, Robert F Casper, Keith E Latham, Susannah VarmuzaAbstract:The newly fertilized Preimplantation Embryo depends entirely on maternal mRNAs and proteins deposited and stored in the oocyte prior to its ovulation. If the oocyte is not sufficiently equipped with maternally stored products, or if zygotic gene expression does not commence at the correct time, the Embryo will die. One of the major abnormalities observed during early development is cellular fragmentation. We showed previously that cellular fragmentation in human Embryos can be attributed to programmed cell death (PCD). Here, we demonstrate that the PCD that occurs during the 1-cell stage of mouse Embryogenesis is likely to be regulated by many cell death genes either maternally inherited or transcribed from the Embryonic genome. We have demonstrated for the first time the temporal expression patterns of nine cell death regulatory genes, and our preliminary experiments show that the expression of these genes is altered in Embryos undergoing fragmentation. The expression of genes involved in cell death (MA-3, p53, Bad, and Bcl-xS) seems to be elevated, whereas the expression of genes involved in cell survival (Bcl-2) is reduced. We propose that PCD may occur by default in Embryos that fail to execute essential developmental events during the first cell cycle.
Carlos Simon - One of the best experts on this subject based on the ideXlab platform.
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soluble ligands and their receptors in human Embryo development and implantation
Endocrine Reviews, 2015Co-Authors: George Anthony Thouas, Carlos Simon, Francisco Dominguez, Mark P Green, Felipe Vilella, David K GardnerAbstract:Extensive evidence suggests that soluble ligands and their receptors mediate human Preimplantation Embryo development and implantation. Progress in this complex area has been ongoing since the 1980s, with an ever-increasing list of candidates. This article specifically reviews evidence of soluble ligands and their receptors in the human Preimplantation stage Embryo and female reproductive tract. The focus will be on candidates produced by the human Preimplantation Embryo and those eliciting developmental responses in vitro, as well as endometrial factors related to implantation and receptivity. Pathways to clinical translation, including innovative diagnostics and other technologies, are also highlighted, drawing from this collective evidence toward facilitating joint improvements in Embryo quality and endometrial receptivity. This strategy could not only benefit clinical outcomes in reproductive medicine but also provide broader insights into the peri-implantation period of human development to improve fetal and neonatal health.
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soluble ligands and their receptors in human Embryo development and implantation
Endocrine Reviews, 2015Co-Authors: George Anthony Thouas, Carlos Simon, Francisco Dominguez, Mark P Green, Felipe Vilella, David K GardnerAbstract:Extensive evidence suggests that soluble ligands and their receptors mediate human Preimplantation Embryo development and implantation. Progress in this complex area has been ongoing since the 1980s, with an ever-increasing list of candidates. This article specifically reviews evidence of soluble ligands and their receptors in the human Preimplantation stage Embryo and female reproductive tract. The focus will be on candidates produced by the human Preimplantation Embryo and those eliciting developmental responses in vitro, as well as endometrial factors related to implantation and receptivity. Pathways to clinical translation, including innovative diagnostics and other technologies, are also highlighted, drawing from this collective evidence toward facilitating joint improvements in Embryo quality and endometrial receptivity. This strategy could not only benefit clinical outcomes in reproductive medicine but also provide broader insights into the peri-implantation period of human development to improve f...
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impact of chromosomal abnormalities on Preimplantation Embryo development
Prenatal Diagnosis, 2007Co-Authors: Carmen Rubio, Carlos Simon, Lorena Rodrigo, Tugce Pehlivan, Amparo Mercader, E Mateu, Pilar Buendia, Thamara Viloria, Ma Jose De Los Santos, J RemohiAbstract:Objectives To evaluate the influence of numerical chromosomal abnormalities on Preimplantation Embryo development. Methods This study includes 6936 Embryos from 1245 women undergoing Preimplantation genetic diagnosis (PGD). Indications for aneuploidy screening were: recurrent miscarriages, implantation failure, severe male factor, advanced maternal age, and mixed causes. Embryo biopsy was performed on day 3, and Embryos were co-cultured until day 5, when Embryo transfer was performed. Results In the aneuploidy screening regimen, normal euploid Embryos showed significantly higher blastocyst rates (68.2%) compared to chromosomally abnormal (42.8%, p < 0.0001) and mosaic (53.7%, p < 0.0001) Embryos. Among aneuploid Embryos for autosomes, higher blastocyst rates were observed in trisomies than monosomies, although only statistically significant in patients over 36 years of age (50.8 vs 38.9%; p < 0.0001). In contrast, in Embryos with sex chromosomes aneuploidy, similar blastocyst rates were observed between trisomies and monosomy X. Conclusion Embryos with certain types of chromosomal abnormalities were negatively selected during Preimplantation Embryo development. Despite this selection, a remarkable percentage of chromosomally abnormal Embryos can develop normally to blastocyst stage with high probability of implantation and pregnancy. Copyright © 2007 John Wiley & Sons, Ltd.