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11 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.

  • Does the meiotic spindle really predicts embryo implantation and live birth rates? An update

  • Sabela García-Oro, Diana Valverde
  • Journal:
    Zygote / Volume 27 / Issue 1 / February 2019
    Published online by Cambridge University Press:
    05 December 2018, pp. 1-4

  • The aim of this study was to determine the capacity of the meiotic spindle (MS) to predict embryo implantation and live birth rates. For this purpose, we performed a broad systematic literature search. Of all publications retrieved, only those in which the implantation rates were related to some characteristics of the MS were evaluated. Despite the different methodology used in all the chosen studies, presence of the MS in oocytes was found to be positively associated with embryo implantation. Moreover, high retardance values, as well as strict criteria of normality in the MS structure, are significantly related to higher embryo implantation numbers and live birth rates.

  • 14 - Glucocorticoids and placental programming

  • Edited by Graham J. Burton, David J. P. Barker, Ashley Moffett, Kent Thornburg
  • Book:
    The Placenta and Human Developmental Programming
    Published online:
    04 February 2011
    Print publication:
    16 December 2010, pp 175-187

  • Summary

    This chapter considers the susceptibility of the early stages of mammalian development before embryo implantation, and even before fertilization has occurred. Maternal obesity and high body mass index (BMI) are associated with reduced fertility and an increased risk of miscarriage in both natural and assisted pregnancies. The pre-implantation embryo has received significant attention in recent years with respect to environmental effects on short- and long-term gestational development, and health into adulthood. Pre-implantation embryos during either early cleavage or until blastocyst formation are cultured in vitro for in vitro fertilization (IVF) and assisted reproductive technologies (ART) treatments. DNA methylation patterns are extensively remodeled during pre-implantation development, thereby providing a potential window for epigenetic sensitivity to environmental conditions. Maternal nutritional restriction during the periconceptional period leads to adverse developmental programming during fetal and postnatal life in domestic animal models.

  • Chapter 26 - Late pregnancy loss

  • 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 277-286

  • Summary

    This chapter describes the principal putative causes of implantation failure and reviews therapeutic strategies. Recurrent implantation failure is a significant and distressing clinical problem. Adjuvant medical therapies to those required for ovarian hyperstimulation are frequently applied for improving embryo implantation and particularly when the clinician is faced with recurrent implantation failure. The appropriate management of the medically complicated patient presenting for in-vitro fertilization (IVF) can be complex and often requires an interdisciplinary approach. Standard ovarian hyperstimulation and the resultant supraphysiological estradiol levels have been shown to impact negatively on endometrial receptivity and embryo quality. Studies of mild ovarian stimulation regimens have shown encouraging results. Although fewer embryos are obtained, an increased percentage of euploid embryos per number of oocytes retrieved have been reported. Significant improvements in clinical pregnancy rates can be achieved by giving due attention to embryo transfer technique.

  • Chapter 15 - Ultrasonography of pelvic endometriosis

  • from Section 2: - Ultrasonography in infertility
  • Edited by Botros R. M. B. Rizk, University of South Alabama
  • Book:
    Ultrasonography in Reproductive Medicine and Infertility
    Published online:
    07 September 2011
    Print publication:
    25 March 2010, pp 119-125

  • Summary

    Power Doppler ultrasound (US), in combination with three-dimensional US and virtual organ computer-aided analysis (VOCAL), is a very good approach for investigating the global ovarian vascular network and its correlation with ovarian response in assisted reproductive technology (ART). An ovarian vascular map is easily obtained from a sagittal section of the ovary. Three-dimensional US has become a key tool for diagnosing uterine malformations. Leiomyomas and endometrial polyps are the most frequent benign uterine pathologies, and both can interfere with the reproductive process. The human endometrium undergoes intense angiogenesis during menstrual cycle, and angiogenesis is a key process for successful embryo implantation and development. In reproductive medicine, it is crucial to exclude ectopic pregnancy as early as possible. 3D US is a more accurate technique for evaluating the relationship between the gestational sac and uterine septum and for differentiating between a cornual pregnancy and a displaced intracavitary pregnancy.

  • 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).

  • 48 - Oocyte Donation

  • from PART III - 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 443-447

  • Summary

    Pregnancy rates obtained with oocyte donation (OD) are the highest when compared to any other assisted reproduction technique (ART). OD is not only the solution for many infertile couples but also a reference model for obtaining useful knowledge of the physiology of reproduction and consequently to be applied in other ART. One of the controversies regarding ovarian stimulation for in vitro fertilization (IVF) regards the impact that successive cycles could have on oocyte recovery in terms of quality and quantity of the obtained oocytes. Age of the recipient, smoking, body mass index (BMI), and endometriosis are the various factors influencing embryo implantation. Endometriosis could affect uterine receptivity through alteration of the local environment by means of endocrine and paracrine mechanisms or due to changes in immune response. Gonadotropin-releasing hormone (GnRH) analogs could have a positive effect on the physiology of endometrial cells of patients with endometriosis.

  • 38 - Medical Strategies to Improve ART Outcome: Current Evidence

  • from PART III - 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 349-360

  • Summary

    This chapter describes five sequential medical steps to successful implantation and reviews the evidence supporting their efficacy and safety. The steps are: selection and preparation of the patient, optimizing the ovarian stimulation protocol, analysing the need of adjuvant medical therapies, embryo transfer and management of the luteal phase. Aspirin, nitric oxide donors, aromatase inhibitors, ascorbic acid, glucocorticoids and insulin-sensitizing drugs are the commonly used adjuvant drugs. Luteal phase length can be restored by stimulating the corpora lutea with human chorionic gonadotropin (hCG) (luteal phase support) or supplementation with progesterone. Improving embryo implantation continues to pose a major challenge to clinicians. While much progress has been made in technical aspects of in vitro fertilization (IVF) treatment to optimize embryo quality and stimulation regimens, it is becoming increasingly clear that patient-related factors may be just as important or more important in determining the chance of success of treatment.

  • 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.

  • 15 - To implant or not to implant: the role of leukaemia inhibitory factor

  • 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 185-202

  • Summary

    This chapter deals with the role of leukaemia inhibitory factor (LIF) at the time of embryo implantation. LIF is involved in endometrial function in humans and domestic species. The lack of LIF signalling in a pregnant female prevents implantation, showing that the action of LIF in the uterus is essential for this process. The absence of LIF has recently been shown to result in low levels of a number of progesterone-responsive genes in the uterus In LIF-null mice, pinopods do not develop over the apical cell membranes, which remain microvillous up to day 7 of pregnancy. Transcript analysis of expression at the implantation site in LIF-null mice suggests molecular abnormalities associated with the lack of decidualisation. One of the most distinctive aspects of the LIF-null phenotype is the complete absence at the implantation site of expression of oncostatin M (OSM), a member of the interleukin 6 (IL6) family.