Category Archives: Human Reproduction

Background

The purpose of this study was first to give an overview of the historical development of polarization microscopy, second to describe the various applications of this technique in assisted reproduction techniques (ART) and third to discuss the potential benefit of polarization microscopy as a predictor for IVF success.

Methods

The history of polarization microscopy was undertaken by performing a backward search in the scientific literature using Google and internet sites of several Societies for Microscopy and Cell Biology. Studies of polarization microscopy in ART were identified by using a systematic literature search in PubMed and Scopus.

Results

A total of 62 articles were identified by the direct search and further relevant articles were found by screening the cited literature in these articles. The topics relevant for assisted reproduction were spindle and zona imaging in combination with IVF success, meiotic cell cycle progression, pharmaceutical studies and cryopreservation. A separate topic was the use of sperm birefringence in ART.

Conclusions

The majority of studies are observational studies and were not performed in a randomized manner and there is no direct comparison of techniques using other gamete selection markers. Despite this, most studies show that polarization microscopy may help us to further increase our knowledge on gametes and meiosis. Whether certain applications such as spindle or zona imaging may lead to an increase in IVF success is unclear at present. Publications on the use of polarization microscopy on sperm are still very limited.

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BACKGROUND

Endometriosis is usually diagnosed by an invasive procedure such as a laparoscopy. Great interest therefore lies in the potential to identify biomarkers which may be surrogates of disease presence or activity, especially relating to the effects of therapy. We have reviewed the existing literature on endometrial differences in women with endometriosis, and assess their potential use as disease biomarkers.

METHODS

We used QUADAS (Quality Assessment of Diagnostic Accuracy Studies) criteria to conduct a systematic review of published papers over the past 25 years on the subject of endometrial differences in endometriosis. We searched for all studies assessing differences between eutopic endometrium of women with and without endometriosis.

RESULTS

We identified 182 relevant articles that are summarized in the review. These studies assess over 200 potential biomarkers, including hormones and their receptors (n = 29), cytokines (n = 25), factors identified using proteomics (n = 8) and histological analysis (n = 10) of endometrial tissue. Sensitivity and specificity were reported or could be calculated for only 32 articles, and ranged from 0 to 100%. Of the nine highest quality studies, six identified putative biomarkers related to nerve fibre growth or cell cycle control, highlighting these areas as promising candidates for future biomarker research.

CONCLUSIONS

This systematic review identified several reports of endometrial differences which have the potential to be biomarkers of endometriosis. However, larger studies in well-defined populations are clearly required to determine their true usefulness.

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BACKGROUND

Endometriosis is a complex disease with a multifactorial pathogenesis, which is crucially dependent on the development of new blood vessels. Based on the current literature, the present review highlights the fact that the neovascularization of endometriotic lesions is not only driven by angiogenesis, but also involves de novo formation of microvessels from circulating endothelial progenitor cells (EPCs). This process, termed post-natal vasculogenesis, is a characteristic of various pathogenic conditions, such as tumour growth and atherosclerosis, and typically comprises the activation, mobilization and recruitment of bone marrow-derived EPCs to the sites of tissue hypoxia.

METHODS

Literature searches were performed in PubMed, MEDLINE and ISI Web of Knowledge for publications focusing on vasculogenesis in the endometrium and endometriotic lesions.

RESULTS

Recent studies indicate that up to 37% of the microvascular endothelium of ectopic endometrial tissue originates from EPCs, partly controlled by the stromal-cell-derived factor-1/chemokine receptor type 4 axis. Accordingly, blockade of EPC recruitment effectively inhibits the formation of microvascular networks in developing endometriotic lesions, indicating that vasculogenesis represents an integral part of the pathogenesis of endometriosis.

CONCLUSIONS

The involvement of vasculogenesis in endometriosis may offer the exciting opportunity for the future establishment of novel diagnostic and therapeutic strategies for this frequent gynaecological disease.

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BACKGROUND

Although chromosomal mosaicism in human preimplantation embryos has been described for almost two decades, its exact prevalence is still unknown. The prevalence of mosaicism is important in the context of preimplantation genetic screening in which the chromosomal status of an embryo is determined by the analysis of a single cell from that embryo.

METHODS

Here we report a systematic review and meta-analysis of studies on the chromosomal constitution of human preimplantation embryos. In 36 studies, out of 2117 citations that met our search criteria, data were provided extensively enough to allow classification of each analysed embryo with prespecified criteria for its chromosomal makeup. The main outcome of this classification was the prevalence of chromosomal mosaicism in human preimplantation embryos.

RESULTS

A total of 815 embryos could be classified. Of these, 177 (22%) were diploid, 599 (73%) were mosaic, of which 480 (59% of the total number of embryos) were diploid–aneuploid mosaic and 119 (14% of the total number of embryos) were aneuploid mosaic, and 39 (5%) contained other numerical chromosomal abnormalities. The distribution of the embryos over these categories was associated with the developmental stage of the embryos, the method used for analysis and the number of chromosomes analysed.

CONCLUSIONS

Diploid–aneuploid mosaicism is by far the most common chromosomal constitution in spare human preimplantation embryos after IVF. This undermines the reliable determination of the ploidy status of a cleavage-stage embryo based on the analysis of a single cell. Future research should determine the origin and developmental potential of mosaic embryos.

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BACKGROUND

Thyroid dysfunction and thyroid autoimmunity are prevalent among women of reproductive age and are associated with adverse pregnancy outcomes. Preconception or early pregnancy screening for thyroid dysfunction has been proposed but is not widely accepted. We conducted a systematic review of the literature on the clinical significance of thyroid dysfunction and thyroid autoimmunity before conception and in early pregnancy.

METHODS

Relevant studies were identified by searching Medline, EMBASE and the Cochrane Controlled Trials Register.

RESULTS

From a total of 14 208 primary selected titles, 43 articles were included for the systematic review and 38 were appropriate for meta-analyses. No articles about hyperthyroidism were selected. Subclinical hypothyroidism in early pregnancy, compared with normal thyroid function, was associated with the occurrence of pre-eclampsia [odds ratio (OR) 1.7, 95% confidence interval (CI) 1.1–2.6] and an increased risk of perinatal mortality (OR 2.7, 95% CI 1.6–4.7). In the meta-analyses, the presence of thyroid antibodies was associated with an increased risk of unexplained subfertility (OR 1.5, 95% CI 1.1–2.0), miscarriage (OR 3.73, 95% CI 1.8–7.6), recurrent miscarriage (OR 2.3, 95% CI 1.5–3.5), preterm birth (OR 1.9, 95% CI 1.1–3.5) and maternal post-partum thyroiditis (OR 11.5, 95% CI 5.6–24) when compared with the absence of thyroid antibodies.

CONCLUSIONS

Pregnant women with subclinical hypothyroidism or thyroid antibodies have an increased risk of complications, especially pre-eclampsia, perinatal mortality and (recurrent) miscarriage. Future research, within the setting of clinical trials, should focus on the potential health gain of identification, and effect of treatment, of thyroid disease on pregnancy outcome.

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BACKGROUND

There is uncertainty over whether maternal smoking is associated with birth defects. We conducted the first ever comprehensive systematic review to establish which specific malformations are associated with smoking.

METHODS

Observational studies published 1959–2010 were identified (Medline), and included if they reported the odds ratio (OR) for having a non-chromosomal birth defect among women who smoked during pregnancy compared with non-smokers. ORs adjusted for potential confounders were extracted (e.g. maternal age and alcohol), otherwise unadjusted estimates were used. One hundred and seventy-two articles were used in the meta-analyses: a total of 173 687 malformed cases and 11 674 332 unaffected controls.

RESULTS

Significant positive associations with maternal smoking were found for: cardiovascular/heart defects [OR 1.09, 95% confidence interval (CI) 1.02–1.17]; musculoskeletal defects (OR 1.16, 95% CI 1.05–1.27); limb reduction defects (OR 1.26, 95% CI 1.15–1.39); missing/extra digits (OR 1.18, 95% CI 0.99–1.41); clubfoot (OR 1.28, 95% CI 1.10–1.47); craniosynostosis (OR 1.33, 95% CI 1.03–1.73); facial defects (OR 1.19, 95% CI 1.06–1.35); eye defects (OR 1.25, 95% CI 1.11–1.40); orofacial clefts (OR 1.28, 95% CI 1.20–1.36); gastrointestinal defects (OR 1.27, 95% CI 1.18–1.36); gastroschisis (OR 1.50, 95% CI 1.28–1.76); anal atresia (OR 1.20, 95% CI 1.06–1.36); hernia (OR 1.40, 95% CI 1.23–1.59); and undescended testes (OR 1.13, 95% CI 1.02–1.25). There was a reduced risk for hypospadias (OR 0.90, 95% CI 0.85–0.95) and skin defects (OR 0.82, 0.75–0.89). For all defects combined the OR was 1.01 (0.96–1.07), due to including defects with a reduced risk and those with no association (including chromosomal defects).

CONCLUSIONS

Birth defects that are positively associated with maternal smoking should now be included in public health educational materials to encourage more women to quit before or during pregnancy.

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