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10 results

  • The role of microRNAs in the regulation of critical genes and signalling pathways that determine endometrial receptivity

  • Yumei Wang, Zhongxiang Ji, Ni Yao, Ximin Hu, Ran Zhou, Xingping Wang, Zhuoma Luoreng
  • Journal:
    Zygote / Volume 32 / Issue 4 / August 2024
    Published online by Cambridge University Press:
    18 September 2024, pp. 261-270
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  • Endometrial receptivity is the ability of the endometrium to accept embryos. Thus, endometrial receptivity dysfunction is an important factor leading to embryo implantation failure. A good endometrial receptivity provides a suitable environment for embryo implantation, improving the embryo implantation rate. The “implantation window” stage, or the receptive stage of the endometrium, is regulated by various hormones, genes, proteins and cytokines, among which microRNAs (miRNAs) and their target genes have a regulatory effect on endometrial receptivity. This review outlines the relationship between endometrial receptivity and pregnancy, the mRNAs and related signalling pathways that regulate endometrial receptivity, and the regulatory role of miRNA in endometrial receptivity, providing a deeper understanding of the regulatory mechanisms of miRNA on endometrial receptivity in humans and animals and reference for the endometrial receptivity-related research.

  • 13A - Corticosteroid Therapy Is Useful in Assisting Implantation

  • from Section II - IVF Add-ons
  • Edited by Roy Homburg, Adam H. Balen, Robert F. Casper
  • Book:
    50 Big Debates in Reproductive Medicine
    Published online:
    25 November 2021
    Print publication:
    16 December 2021, pp 68-70

  • Summary

    Implantation is a complex biological process and for the maternal tolerance of an antigenically different fetus, controlled inflammation and activation of immune response in the peri-implantation period is essential. Elevated follicular cortisol:cortisone ratio is associated with good follicular development, oocyte maturation and successful implantation. However, as the follicles are unable to biosynthesise cortisol, corticosteroid therapy has been tested and shown to improve clinical pregnancy in women having stimulated IVF/ICSI cycles. Corticosteroid gradient at the feto-maternal interface is essential and is facilitated by progesterone induced 11βHSD-I activity. In women with recurrent miscarriage, expression of 11βHSD-I in decidualising endometrium is blunted by high uterine natural killer (uNK) cell density, which also has a negative impact on decidualisation marker genes and endometrial cytokines, suggesting that local steroid deficiency leads to impaired decidualisation. Prednisolone has been shown to reduce uNK cell density and although a pilot RCT suggested possible clinical benefit, validation from larger trials is awaited.

  • Chapter 22 - Morphometric analyses of embryos

  • Edited by David K. Gardner, University of Melbourne, Botros R. M. B. Rizk, University of South Alabama, Tommaso Falcone
  • Book:
    Human Assisted Reproductive Technology
    Published online:
    16 May 2011
    Print publication:
    31 March 2011, pp 248-259

  • Summary

    This chapter reviews the current status of assisted reproduction techniques in the light of the best evidence available. In order to optimize the results of assisted reproduction, various laboratory modifications have been suggested. These include performing Intracytoplasmic sperm injection (ICSI) rather than in vitro fertilization (IVF) for all oocytes, using co-culturing techniques, assisted hatching techniques, as well as selecting the embryos with the best potential for implantation based on their morphology, their metabolism, or by prolonging their culture in vitro to the blastocyst stage. Embryo transfer (ET) is arguably the most critical step in assisted reproduction and the least successful. Various attempts have been made to improve endometrial receptivity in order to increase the clinical outcome of IVF and ICSI. These include various regimens of luteal support, the use of corticosteroids, the removal of hydrosalpinges, diminishing uterine contractions as well as enhancing the endometrial blood flow.

  • Chapter 23 - Embryo reduction in multiple pregnancies

  • Edited by Roy G. Farquharson, University of Liverpool, Mary D. Stephenson, University of Chicago
  • Book:
    Early Pregnancy
    Published online:
    05 October 2010
    Print publication:
    09 September 2010, pp 245-254

  • Summary

    This chapter summarizes the hormonal regulation and molecular bases of endometrial receptivity, its clinical implication and the possible models to study this complex process and to develop functional assays in vitro. Cyclic changes of the endometrium have been well described at the light microscopy level. A large amount of research worldwide has been focused on the problem of finding a specific marker(s) of uterine (endometrial) receptivity-biomarkers that can be useful for the diagnosis and treatment of couples with infertility of endometrial origin. The main techniques used to study the features of the receptive endometrium include microscopy for endometrial morphology, quantitative PCR, in situ hybridization and gene expression microarrays in endometrial biopsy. The ultimate in vitro model to study endometrial receptivity and embryonic implantation would contain all the cell types of the endometrium so that the complex interactions between the maternal tissue and the blastocyst could be characterized.

  • 4 - Endometrial Receptivity

  • from PART I - PHYSIOLOGY OF REPRODUCTION
  • Edited by Botros R. M. B. Rizk, University of South Alabama, Juan A. Garcia-Velasco, Hassan N. Sallam, Antonis Makrigiannakis, University of Crete
  • Book:
    Infertility and Assisted Reproduction
    Published online:
    04 August 2010
    Print publication:
    15 September 2008, pp 38-45

  • Summary

    Endometrial receptivity to embryo implantation has been an enduring bottleneck of the reproductive system in humans. The advent of in vitro fertilization (IVF) opened the possibility to revert to donated oocytes for cases of infertility linked to premature ovarian failure (POF). For being effective, however, donor egg IVF required that the endometrium was rendered receptive with the sole use of the exogenous hormones E2 and progesterone. It is likely that part of the benefit of luteal support with exogenous progesterone is mediated by an effect on the myometrium. The luteal phase is characterized by a state of uterine quiescence that is brought by progesterone secreted by the corpus luteum after ovulation. The impact of uterine contractility on IVF outcome stresses the role of precautions that need to accompany ET in an attempt to minimize the impact the measures themselves have on uterine contractions (UC).

  • 74 - The Future of Assisted Reproduction

  • from PART IV - ETHICAL DILEMMAS IN FERTILITY AND ASSISTED REPRODUCTION
  • Edited by Botros R. M. B. Rizk, University of South Alabama, Juan A. Garcia-Velasco, Hassan N. Sallam, Antonis Makrigiannakis, University of Crete
  • Book:
    Infertility and Assisted Reproduction
    Published online:
    04 August 2010
    Print publication:
    15 September 2008, pp 747-758

  • Summary

    The future of assisted reproduction lies in optimization of each treatment phase starting with ovarian stimulation through laboratory procedures, selecting the best embryo for transfer, embryo transfer, luteal phase support leading to pregnancy, and the birth of a healthy single ton baby. Gonadotropin-releasing hormone (GnRH) agonists have changed the course of ovarian stimulation for in vitro fertilization (IVF). GnRH antagonists have been introduced recently in ovarian stimulation for pituitary suppression. High implantation and pregnancy rates in oocyte donation cycles irrespective of acceptors' age imply that ovarian stimulation impairs endometrial receptivity in stimulated cycles. Embryo transfer procedure plays a pivotal role in the success of assisted reproduction. Improving embryo implantation continues to pose a major challenge to clinicians. The future developments in assisted reproduction should encompass individualized approach to ovarian stimulation, vitrification, single blastocyst transfer, and development of new tools for genetic testing.

  • 5 - Molecular Mechanisms of Implantation

  • from PART I - PHYSIOLOGY OF REPRODUCTION
  • Edited by Botros R. M. B. Rizk, University of South Alabama, Juan A. Garcia-Velasco, Hassan N. Sallam, Antonis Makrigiannakis, University of Crete
  • Book:
    Infertility and Assisted Reproduction
    Published online:
    04 August 2010
    Print publication:
    15 September 2008, pp 46-52

  • Summary

    This chapter summarizes the information concerning the systems implicated in the regulation of implantation and endometrial receptivity in humans. If focuses on the chemokine system and the comparison of two similar processes, human implantation and leukocyte transendothelial migration. The chapter presents new strategies based on array technology that aim to clarify the fragmented information existing in the field. Clues about the relevance of the chemokines in the process of implantation come from the chemokine interferon inducible protein 10 kDa (IP-10). IP-10 has been involved in the regulation of blastocyst migration, apposition, and initial adhesion in ruminants. The ultimate goal of DNA microarrays technology is to establish a standard for recording and reporting microarray-based gene expression data, which will in turn facilitate the establishment of databases and public repositories and enable the development of data analysis tools.

  • 23 - Consensus views arising from the 48th Study Group: Implantation and Early Development

  • from SECTION 5 - CONSENSUS VIEWS
  • Edited by Hilary Critchley, University of Edinburgh, Iain Cameron, University of Southampton, Stephen Smith
  • Book:
    Implantation and Early Development
    Published online:
    05 June 2014
    Print publication:
    01 June 2005, pp 283-286

  • Summary

    The multidisciplinary systems biology approach that is needed to assess endometrial receptivity should be used to understand the reciprocal dialogue between the embryo and the decidualised endometrium. This chapter focuses on human embryo research and the development of appropriate functional models of implantation that will allow the investigation of molecules mediating blastocyst-endometrial/decidual interaction. Ectopic pregnancy could be considered as a model to study the failure or the absence of mechanisms that limit implantation. Experience with cell nuclear replacement has identified the key role of cytoplasmic and nuclear factors for normal embryonic development. The conventional measurements of sperm concentration, motility and morphology only act as surrogate markers of fertility. Pre-implantation genetic diagnosis (PGD) should be carried out by specialist centres that have a multidisciplinary genetic support infrastructure including genetic counselling, and clinical pathology accreditation (CPA) qualified cytogenetics and molecular genetics laboratories.

  • 4 - Adhesion molecules and implantation

  • from SECTION 1 - PREPARATION FOR IMPLANTATION – THE UTERINE ENVIRONMENT
  • Edited by Hilary Critchley, University of Edinburgh, Iain Cameron, University of Southampton, Stephen Smith
  • Book:
    Implantation and Early Development
    Published online:
    05 June 2014
    Print publication:
    01 June 2005, pp 49-60

  • Summary

    Experimental studies of human implantation in which embryos hatch and attach to endometrial epithelial cells in monolayer culture have shown that Mucin (MUC1) disappears from a small area of cells that surrounds the attached embryo. The term 'marker' is used advisedly because, while the inclusion criteria include the ability to function as an adhesion molecule, as well as presence at the implantation site, in vivo functional (IVF) evidence is so far mostly lacking. Heparin-binding EGF-like growth factor (HB-EGF) has been suggested to play two different roles: in addition to accelerating embryo development, it has a membrane-bound variant that can mediate intercellular attachment by binding to ErbB4 and heparan sulphate proteoglycan, both of which are present on the blastocyst. Critically, the biochemical dialogue between the embryo and the endometrium that determines endometrial receptivity at the attachment site cannot emerge from an analysis of either one alone.

  • 16 - are gene arrays useful for the study of implantations?

  • from SECTION 3 - LESSONS FROM ANIMAL MODELS (TRANSGENICS) AND NOVEL TECHNOLOGIES
  • Edited by Hilary Critchley, University of Edinburgh, Iain Cameron, University of Southampton, Stephen Smith
  • Book:
    Implantation and Early Development
    Published online:
    05 June 2014
    Print publication:
    01 June 2005, pp 203-216

  • Summary

    This chapter reviews how microarray studies to date have advanced understanding of critical aspects of the biology of implantation and discusses potential applications in the future. All gene arrays for expression profiling depend on hybridisation of complementary strands of DNA or RNA. Progesterone receptor (PR) has long been known to be essential for the preparation of a receptive endometrium, until now relatively little has been known about the molecular pathways regulated by progesterone in the endometrium. One of the novel genes upregulated by progesterone is the lipid-metabolising enzyme leucocyte 12/15-lipoxygenase. In women, the action of the progesterone receptor is also essential for the development of receptivity, which occurs between day luteinising hormone (LH)+5 and day LH+10. The ability of microarrays to analyse thousands of mRNAs simultaneously provides a powerful new approach to the identification of markers of receptivity.