Pinopodes are present in Lif null and Hoxa10 null mice

The RNA-seq based endometrial receptivity test (rsERT) compared to pinopode: A better diagnostic tool for endometrial receptivity for patients with recurrent implantation failure in Chinese population

Displaced window of implantation (WOI) is one of the endometrial origins that accounts for implantation failure, especially for patients with recurrent implantation failure (RIF), yet no standard diagnostic tool has been recognized. The study consists of two parts, aiming to compare the concordance and efficacy of the diagnostic tools, the newly developed RNA-seq based endometrial receptivity test (rsERT) to the conventional pinopode, in diagnosing WOI and guiding personalized embryo transfer (pET). With the same group of RIF patients, the rsERT diagnosed 32 patients (65.31%) with normal WOIs, and most of the displacements were advancements (30.61%). While according to pinopode, only 14 patients (28.57%) were found with normal WOIs, and most patients (63.27%) presented delayed growth patterns. After conducting pET, patients in the rsERT group had higher successful pregnancy rates while requiring fewer ET cycles (50.00% vs. 16.67%, p=0.001). The study proved poor consistency between the diagnostic tools of endometrial receptivity based on cellular structure and gene profiling, and it supported rsERT as a reliable tool with potential clinical value.

Pinopodes: Recent advancements, current perspectives, and future directions

Successful embryo implantation is a complex and highly regulated process involving precise synchronization between the fetal-derived trophoblast cells and maternal uterine luminal epithelium. Multiple endocrine-driven factors are important for controlling the timely receptivity of the uterus, and this complexity underscores implantation failure as a major cause of recurrent infertility associated with assisted reproductive technologies. One particular cellular structure often hypothesized to promote receptivity is the pinopode or uterodome - a hormonally regulated, large cellular protrusion on the uterine epithelial surface. Recent clinical studies associate pinopodes with favorable fertility outcomes in women, and because they are directly linked to an increase in progesterone levels, the potential utility of these hormone-regulated cell biological structures in predicting or improving implantation in a clinical setting holds promise. In this review, we aim to generate interest in pinopodes from the broader cell biology and endocrinology communities, re-examine methodologies in pinopode research, and identify priorities for future investigation of pinopode structure and function in women's reproductive health.

Therapeutic Effects of VEGF Gene-Transfected BMSCs Transplantation on Thin Endometrium in the Rat Model

Objective

Bone mesenchymal stem cells (BMSCs) transplantation has a therapeutic effect on the thin endometrium in animal researches and clinical trials. The present study aims at assessing whether transplantation of VEGF-transfected BMSCs (VEGF-BMSCs) have a better therapeutic effect on endometrial regeneration and endometrial receptivity compared with BMSCs therapy alone.

Methods

Sprague-Dawley (SD) rats were used in the study. Thin endometrium model was established with 95% ethanol injection into uterine. VEGF-BMSCs or BMSCs was transplanted via tail vein IV injection. Endometrial thickness, morphology, and pinopodes were assessed by hematoxylin and eosin (HE) staining and scanning electron microscope (SEM). The proteins and mRNAs expressions of markers for endometrial cells and endometrial receptivity were measured after treatment. The fertility testing was done to assess the embryo implantation efficiency.

Results

VEGF-BMSCs transplantation significantly increased endometrial thickness compared with the BMSCs group and the control group. There was no significant difference in endometrial thickness between VEGF-BMSCs group and sham operation group. Importantly, in protein level, expressions of cytokeratin, vitamin, VEGF, LIF, and integrin α_νβ ₃ in VEGF-BMSC group were increased dramatically compared with those of the control group and BMSC group both 4 days and 8 days after stem cells transplantation. Accordingly, mRNA expression of LIF and integrin α _ν β ₃ was significantly upregulated compared with those of the control group and BMSC group both 4 and 8 days after treatment. The pinopodes were developed better in the VEGF-BMSCs group and the sham operation group compared with BMSCs group and the control group. The number of embryo implantation is largest in the sham operation group, followed by VEGF-BMSCs group, BMSCs group, and the control group.

Conclusions

Transplantation of VEGF gene-transfected BMSCs may be a better therapeutic treatment for thin endometrium than stem cell therapy alone.

Pinopode score around the time of implantation is predictive of successful implantation following frozen embryo transfer in hormone replacement cycles

STUDY QUESTION

Is pinopode measurement of any prognostic value?

SUMMARY ANSWER

Pinopode expression was significantly associated with the occurrence of pregnancy after frozen embryo transfer.

WHAT IS KNOWN ALREADY

Pinopodes are expressed in the endometrium during the implantation period. Pinopode measurement has been proposed as a marker of endometrial receptivity.

STUDY DESIGN, SIZE, DURATION

A prospective cohort study was conducted at the Center of Reproductive Medicine, Sir Run Run Shaw Hospital, between 2014 and 2016, recruiting 172 women with infertility and undergoing frozen embryo transfer following IVF treatment. Among 172 participants, 46 women took part in the first study to quantify the daily changing pattern of pinopodes 3-7 days after the initiation of progesterone therapy in the hormone replacement cycles and the remaining 126 women with infertility participated in a study to examine the relationship between pinopode count and pregnancy outcome following frozen embryo transfer in hormone replacement cycles.

PARTICIPANTS/MATERIALS, SETTING, METHODS

The mean age of participants was 29 years old. All participants received an artificial hormone replacement protocol capable of supporting successful implantation. Endometrial biopsies from 46 women were obtained 3, 4, 5, 6 and 7 days after the initiation of progesterone therapy (P + 3, n = 6; P + 4, n = 6; P + 5, n = 11; P + 6, n = 13; P + 7, n = 10, respectively). Another 126 endometrial biopsies were obtained precisely 6 days after the initiation of progesterone. Scanning electron microscopy was used to capture the pinopode images, followed by use of the image J program to quantify the count and subtype of the pinopodes.

MAIN RESULTS AND THE ROLE OF CHANCE

We found that at least 60 microscopic fields were necessary to achieve a reproducible result. An intra-observer variability study showed good agreement between two measurements regarding the developing pinopode (DP) subtype (r = 0.95) and the fully developed pinopode (FDP) subtype (r = 0.86) but not for the regressing (RP) pinopode subtype (r = 0.39). The proportion of DP/total pinopodes (TP) declined rapidly form day P + 4 to a minimum on day P + 6. The percentage of FDP/TP increased rapidly from day P + 4 to reach a peak on day P + 6. On the other hand, the percentage of RP/TP reached a peak on day P + 7. Participants who conceived had a significantly (P = 0.011) higher percentage of FDP/TP on day P + 6 and significantly (P = 0.005) lower percentage of DP/TP on the same day compared with participants who did not become pregnant. Using a scoring system incorporating the percentages of DP and FDP, it was found that the pregnancy rate and the embryo implantation rate of women with a high pinopode score (82.3%; 63.0%) was significantly (P = 0.001; P = 0.046) higher than that of women with a low pinopode score (53.3%; 46.7%), respectively. There remains a possibility that the observations could have arisen due to chance.

LIMITATIONS, REASONS FOR CAUTION

This study examined pinopode count and subtype in the HRT cycles, and it is uncertain whether the same observations apply to in natural cycles.

WIDER IMPLICATIONS OF THE FNDINGS

Pinopodes have been questioned as a potential marker of endometrial receptivity for many years. Our results suggested that pinopode measurement may be of value in predicting pregnancy.

STUDY FUNDING/COMPETING INTEREST(S)

The study was supported by the grants from the general project of medicine and health in Zhejiang Province of China (2015KYA142; 2018KY106), the Key Research and Development Program of Zhejiang Province (2017C03022) and the National Natural Science Foundation of China (81701514).The funders had no role in the study design, data collection and analysis, decision to publish or preparation of the manuscript. We have no competing interests to declare.

TRIAL REGISTRATION NUMBER

ISRCTN26300668.

Adrenomedullin improves fertility and promotes pinopodes and cell junctions in the peri-implantation endometrium

Implantation is a complex event demanding contributions from both embryo and endometrium. Despite advances in assisted reproduction, endometrial receptivity defects persist as a barrier to successful implantation in women with infertility. We previously demonstrated that maternal haploinsufficiency for the endocrine peptide adrenomedullin (AM) in mice confers a subfertility phenotype characterized by defective uterine receptivity and sparse epithelial pinopode coverage. The strong link between AM and implantation suggested the compelling hypothesis that administration of AM prior to implantation may improve fertility, protect against pregnancy complications, and ultimately lead to better maternal and fetal outcomes. Here, we demonstrate that intrauterine delivery of AM prior to blastocyst transfer improves the embryo implantation rate and spacing within the uterus. We then use genetic decrease-of-function and pharmacologic gain-of-function mouse models to identify potential mechanisms by which AM confers enhanced implantation success. In epithelium, we find that AM accelerates the kinetics of pinopode formation and water transport and that, in stroma, AM promotes connexin 43 expression, gap junction communication, and barrier integrity of the primary decidual zone. Ultimately, our findings advance our understanding of the contributions of AM to uterine receptivity and suggest potential broad use for AM as therapy to encourage healthy embryo implantation, for example, in combination with in vitro fertilization.

Activating transcription factor 3 promotes embryo attachment via up-regulation of leukemia inhibitory factor in vitro

BACKGROUND

A receptive endometrium is essential for maternal-embryonic molecular communication during implantation. However, the specific molecular regulatory mechanisms of the endometrial capacity remain poorly understood. Here, we examined activating transcription factor 3 (ATF3) expression in human endometria and the functional effect of ATF3 on embryo attachment in vitro.

METHODS

Immunohistochemistry (IHC) was used to assess the ATF3 expression patterns in human endometria. Quantitative real-time PCR (qRT-PCR), western blotting and immunofluorescence (IF) studies were applied to explore ATF3 expression in Ishikawa cells upon estrogen (E₂) and medroxyprogesterone acetate (MPA) treatment. qRT-PCR and western blotting were performed to inspect LIF (leukemia inhibitory factor) expression after enhancement or inhibition of ATF3, and a luciferase reporter assay and ChIP-PCR were used to confirm the regulatory mechanism of ATF3 to LIF. Endometrial epithelial capacity was assessed by an in vitro model of attachment of BeWo spheroids to Ishikawa cells. Western blotting was performed to compare the expression of ATF3 in endometrial samples of recurrent implantation failure (RIF) patients with that in samples from fertile women (FER) who had undergone no less than one successful embryo transplantation.

RESULTS

ATF3 was located in human endometrial epithelial cells and stromal cells and was significantly induced by E₂ and MPA in Ishikawa cells. Adenovirus-mediated overexpression of ATF3 in Ishikawa cells activated LIF promoter activity and enhanced its expression. Accordingly, the stimulation of BeWo spheroid adhesion promoted by ATF3 was inhibited by pretreatment with a specific antibody against LIF via the antibody-blocking assay. Moreover, ATF3 was aberrantly decreased in the endometria of RIF patients.

CONCLUSIONS

Our findings suggest that ATF3 plays a significant role in regulating human endometrial receptivity and embryo attachment in vitro via up-regulation of leukemia inhibitory factor.

TRIAL REGISTRATION

Construction and management of the Nanjing multi-center biobank. No. 2013-081-01 . Registered 10 Dec. 2013.

The Protective Effect of N-Acetylcysteine on Ionizing Radiation Induced Ovarian Failure and Loss of Ovarian Reserve in Female Mouse

Ionizing radiation may cause irreversible ovarian failure, which, therefore, calls for an effective radioprotective reagent. The aim of the present study was to evaluate the potential radioprotective effect of N-acetylcysteine (NAC) on ionizing radiation induced ovarian failure and loss of ovarian reserve in mice. Kun-Ming mice were either exposed to X-irradiation (4 Gy), once, and/or treated with NAC (300 mg/kg), once daily for 7 days before X-irradiation. We examined the serum circulating hormone levels and the development of ovarian follicles as well as apoptosis, cell proliferation, and oxidative stress 24 hours after X-irradiation. In addition, morphological observations on the endometrial luminal epithelium and the fertility assessment were performed. We found that NAC successfully restored the ovarian and uterine function, enhanced the embryo implantation, improved the follicle development, and altered the abnormal hormone levels through reducing the oxidative stress and apoptosis level in granulosa cells while promoting the proliferation of granulosa cells. In conclusion, the radioprotective effect of NAC on mice ovary from X-irradiation was assessed, and our results suggested that NAC can be a potential radioprotector which is capable of preventing the ovarian failure occurrence and restoring the ovarian reserve.

Altered expression of hormone receptor, integrin β3 and pinopode in the endometrium of luteal phase defect women

OBJECTIVE

To invistigate estrogen receptor (ER), progesterone receptor (PR), integrin β3, and pinopode expression in luteal phase deficiency (LPD) women.

METHODS

There were 52 nulligravidas consecutive infertile patients undergoing a routine assistant reproduction consultation included in this study. An endometrial biopsy sample was randomly obtained between days 4 and 10 of the luteal phase. Endometrial morphology was examined with scanning electron microscopy. Expressions of ER, PR, integrin β3 were determined in the endometrium of LPD patients with immunohistochemistry.

RESULTS

The incidence of LPD was 15.3% (8/52) in this study. On day luteinizing hormone (LH) surge + 9∼LH + 10, noted regressing pinopodes resembling a day LH + 7∼LH + 8 in the endometrium of the control group. The expressions of ER and PR in glandular epithelium were significantly increased in endometrium of LPD than that in the control group (p < 0.05). In contrast, there was a statistically significant decrease expression of the integrin β3 in women from the group of LPD (p < 0.05).

CONCLUSION

The altered expression of ER and PR may be associated with the expression variation of integrin and pinopode formation in endometrium of LPD women. This alteration may imply the association of low rates of cycle fecundity and high rates of embryonic loss in LPD women.

Dysregulated leukemia inhibitory factor and its receptor regulated signal transducers and activators of transcription 3 pathway: a possible cause for repeated implantation failure in women with dormant genital tuberculosis?

OBJECTIVE

To investigate the influence of dormant Mycobacterium tuberculosis on the expression of various endometrial receptivity markers and leukemia inhibitory factor (LIF)-signal transducers and activators of transcription 3 (STAT3) signaling pathway. Expression of endometrial receptivity markers and LIF-STAT3 signaling in in vitro decidualized human endometrial stromal cells (hESC) treated with 65 kDa mycobacterial heat shock protein (HSP65) is also explored.

DESIGN

A prospective study.

SETTING

Tertiary care hospital and reproductive health research unit.

PATIENT(S)

Endometrial tissue samples were collected from 38 women who tested positive for Mycobacterium tuberculosis and 30 normal women with proven fertility undergoing sterilization. In vitro decidualization of hESC was performed.

INTERVENTION(S)

Endometrial biopsies collected from all women during implantation window and treatment of hESC with HSP65.

MAIN OUTCOME MEASURE(S)

Measurement of various endometrial receptivity markers including αvβ3 integrin, E-cadherin, MECA-79, mucin-1, and pinopodes and LIF/LIFR-STAT3 signaling molecules expressed in the endometrium of women with dormant genital tuberculosis (GTB) during implantation window and measured also in HSP65-treated hESC.

RESULT(S)

Significantly reduced levels of endometrial receptivity markers LIF, LIFR, and pSTAT3 were observed in endometrium of women with dormant GTB as compared with controls. A similar trend was observed under in vitro conditions with decreased level of phosphorylated STAT3 in HSP65-treated hESC. However, no change in the expression of endometrial receptivity markers under in vitro conditions was observed.

CONCLUSION(S)

Our findings suggest that endometrium of women with dormant GTB is associated with poor receptivity, as evidenced by reduced receptivity markers and aberrant LIF-STAT3 signaling. In vitro treatment of hESC with HSP65 also confirms compromised endometrial decidualization.

The LIF-mediated molecular signature regulating murine embryo implantation

The establishment of a receptive uterus is the prime requirement for embryo implantation. In mice, the E2-induced cytokine leukemia inhibitory factor (LIF) is essential in switching the uterine luminal epithelium (LE) from a nonreceptive to a receptive state. Here we define the LIF-mediated switch using array analysis and informatics to identify LIF-induced changes in gene expression and annotated signaling pathways specific to the LE. We compare gene expression profiles at 0, 1, 3, and 6 h, following LIF treatment. During the first hour, the JAK-STAT signaling pathway is activated and the expression of 54 genes declines, primarily affecting LE cytoskeletal and chromatin organization as well as a transient reduction in the progesterone, TGFbetaR1, and ACVR1 receptors. Simultaneously 256 genes increase expression, of which 42 are transcription factors, including Sox, Kfl, Hes, Hey, and Hox families. Within 3 h, the expression of 3987 genes belonging to more than 25 biological process pathways was altered. We confirmed the mRNA and protein distribution of key genes from 10 pathways, including the Igf-1, Vegf, Toll-like receptors, actin cytoskeleton, ephrin, integrins, TGFbeta, Wnt, and Notch pathways. These data identify novel LIF-activated pathways in the LE and define the molecular basis between the refractory and receptive uterine phases. More broadly, these findings highlight the staggering capacity of a single cytokine to induce a dynamic and complex network of changes in a simple epithelium essential to mammalian reproduction and provide a basis for identifying new routes to regulating female reproduction.

Sophoricoside fails the embryo implantation by compromising the uterine endometrial receptivity at implantation "window" of pregnant mice

Sophoricoside (SOPH) is an isoflavone glycoside isolated from the fruits of Sophora japonica. Since its first isolation in 1961, there are rare findings about the effects of SOPH on reproductive system. In the present study, the pregnant mice administrated by different doses of SOPH were used to explore the effect of SOPH on embryo implantation, especially on the endometrial receptivity. The statistical results showed that the number of implanted embryos was gradually declining along the increasing dose of SOPH. When the administrated dose of SOPH was 600 mg/kg per day, great changes were observed in the exposed uterine morphology and up-regulated progesterone receptor (PR) and down-regulated estrogen receptor α (ERα), E-cadherin, matrix metalloproteinase-2 (MMP-2) and integrin β3 were also found in SOPH-exposed uterine. These findings demonstrated that SOPH exposure reduced the number of implanted embryos in a dose-dependent manner and failed the embryo implantation through altering the morphology of uterine and compromising the endometrial receptivity.

Pinopodes, leukemia inhibitory factor, integrin-β3, and mucin-1 expression in the peri-implantation endometrium of women with unexplained recurrent pregnancy loss

OBJECTIVE

To compare pinopode morphology and coverage, and expression of leukemia inhibitory factor (LIF), integrin-β3, and mucin-1 (MUC1) in the peri-implantation endometrium of women with unexplained recurrent pregnancy loss (RPL) versus normal fertile women.

DESIGN

Exploratory clinical study.

SETTING

University-affiliated assisted reproductive center.

PATIENT(S)

Women undergoing assisted reproduction at centers of reproductive medicine in two university teaching hospitals.

INTERVENTION(S)

Endometrial biopsy samples were obtained from women with RPL (test group, n = 30) and normal fertile women (control group, n = 26) 7 days after the day of luteinizing hormone peak. Pinopode morphology and coverage were assessed by use of scanning electron microscopy. Expression of LIF, integrin β3, and MUC1 were evaluated by immunohistochemical staining.

MAIN OUTCOME MEASURE(S)

Pinopode morphology and coverage, and the expression of LIF, integrin-β3, and MUC1 in both groups.

RESULT(S)

Pinopode morphology and coverage, and the expression of LIF and integrin-β3 showed no statistically significant differences between the two groups. The expression of MUC1 was statistically significantly reduced in the glandular epithelial cells and endometrial lumen of the RPL group compared with controls.

CONCLUSION(S)

The morphology and the coverage of pinopodes and expression of LIF and integrin-β3 did not change, but MUC1 expression was statistically significantly reduced in women with RPL compared with normal women.

High throughput, cell type-specific analysis of key proteins in human endometrial biopsies of women from fertile and infertile couples

BACKGROUND

Although histological dating of endometrial biopsies provides little help for prediction or diagnosis of infertility, analysis of individual endometrial proteins, proteomic profiling and transcriptome analysis have suggested several biomarkers with altered expression arising from intrinsic abnormalities, inadequate stimulation by or in response to gonadal steroids or altered function due to systemic disorders. The objective of this study was to delineate the developmental dynamics of potentially important proteins in the secretory phase of the menstrual cycle, utilizing a collection of endometrial biopsies from women of fertile (n = 89) and infertile (n = 89) couples.

METHODS AND RESULTS

Progesterone receptor-B (PGR-B), leukemia inhibitory factor, glycodelin/progestagen-associated endometrial protein (PAEP), homeobox A10, heparin-binding EGF-like growth factor, calcitonin and chemokine ligand 14 (CXCL14) were measured using a high-throughput, quantitative immunohistochemical method. Significant cyclic and tissue-specific regulation was documented for each protein, as well as their dysregulation in women of infertile couples. Infertile patients demonstrated a delay early in the secretory phase in the decline of PGR-B (P < 0.05) and premature mid-secretory increases in PAEP (P < 0.05) and CXCL14 (P < 0.05), suggesting that the implantation interval could be closing early. Correlation analysis identified potential interactions among certain proteins that were disrupted by infertility.

CONCLUSIONS

This approach overcomes the limitations of a small sample number. Protein expression and localization provided important insights into the potential roles of these proteins in normal and pathological development of the endometrium that is not attainable from transcriptome analysis, establishing a basis for biomarker, diagnostic and targeted drug development for women with infertility.

Effects of hydrosalpinx on pinopodes, leukaemia inhibitory factor, integrin beta3 and MUC1 expression in the peri-implantation endometrium

OBJECTIVES

To compare the expression of pinopodes, LIF, integrin beta(3) and MUC1 in the peri-implantation endometrium of women with and without hydrosalpinx.

STUDY DESIGN

A prospective observational study in an assisted reproductive unit in a university teaching hospital, including 20 women with hydrosalpinx and 21 women without hydrosalpinx. Endometrial biopsies were performed on day LH+7 or +8. The proportion and density of pinopodes were assessed by scanning electron microscopy. LIF, integrin beta3 and MUC1 were evaluated with immunohistochemical staining.

RESULTS

The proportion and the density of pinopodes were not significantly different between the hydrosalpinx and control groups. The LIF, integrin beta(3), and MUC1 expression were significantly reduced in both glandular epithelial cells and endometrial lumen of the hydrosalpinx group when compared with those of the control group. The expression of integrin beta(3) in stromal cells was also significantly lower in the hydrosalpinx group.

CONCLUSIONS

The proportion and the density of pinopodes in the peri-implantation endometrium were not affected by the presence of hydrosalpinx while LIF, integrin beta(3) and MUC1 were significantly reduced in patients with hydrosalpinx.

Haploinsufficiency for adrenomedullin reduces pinopodes and diminishes uterine receptivity in mice

Adrenomedullin (AM) is a multifunctional peptide vasodilator that signals through a G-protein-coupled receptor when the receptor, called calcitonin receptor-like receptor (CL), is associated with a receptor activity-modifying protein 2 (RAMP2). We demonstrated previously that haploinsufficieny for each of these genes led to reduced maternal fertility, and that even a modest genetic reduction of AM peptide caused maternal defects in implantation, placentation, and fetal growth. Here, we further demonstrate that Adm(+/-) female mice displayed reduced pregnancy success rates that were not caused by defects in folliculogenesis, ovulation, or fertilization. The poor fertility of Adm(+/-) female mice could not be rescued by transfer of wild-type blastocysts, which suggested an underlying defect in uterine receptivity. In fact, we found that Adm, Calcrl, and Ramp2 gene expressions are tightly and spatiotemporally regulated in the luminal epithelial cells of the uterus during the estrus cycle and the peri-implantation period. RAMP3, which also generates an AM receptor when associated with CL, had a diametrically opposite expression pattern than that of Adm, Calcrl, and Ramp2 and was most robustly induced in the stroma of the uterus. Finally, we discovered that Adm(+/-) female mice have a substantially reduced number of pinopodes on the uterine luminal epithelial surface, which is indicative and possibly causative of the poor uterine receptivity. Taken together, our studies identify a new class of pharmacologically tractable proteins that are involved in establishing uterine receptivity through the regulation of pinopode formation.

Disturbances in the LIF pathway in the endometrium among women with unexplained infertility

OBJECTIVE

To study the expression of leukemia inhibitory factor (LIF), its receptors LIFR and gp130, and its inhibitor SOCS1 in endometria from fertile women and infertile women with unexplained infertility. Signaling through the LIF pathway is involved in maintenance of a receptive state of human endometrium. Impaired endometrial receptivity may be a cause of female infertility.

DESIGN

Prospective clinical study.

SETTING

Hospital-based IVF unit and university-affiliated reproductive research laboratories.

PATIENT(S)

Twenty-six healthy fertile women and 14 women with unexplained infertility.

INTERVENTION(S)

Endometrial biopsy.

MAIN OUTCOME MEASURE(S)

Pinopode formation, expression of LIF, LIFR, gp130, and SOCS1 protein and mRNA in endometrial biopsies.

RESULT(S)

The expression of LIFR in the endometrium was negatively correlated to the expression of SOCS1 and positively correlated to the formation of pinopodes. In control fertile women, simultaneous intense apical staining of LIFR and gp130 together with faint SOCS1 staining was observed in epithelial cells, whereas the opposite was seen in most women with unexplained infertility.

CONCLUSION(S)

Unexplained infertility in some women might be explained by disturbances in the LIF pathway in midsecretory-phase endometrium.

Enhanced endocytotic and transcytotic activity in the rat endometrium prior to embryo implantation

BACKGROUND

Understanding the mechanisms by which fluid absorption and secretion occur in the endometrium is clinically important since conditions that deregulate this process reduce fertility. It has been suggested that luminal epithelial cells induce a crucial step in the process of embryo implantation called uterine closure via endocytotic fluid uptake. Uterine lumen closure is a key step in the process of embryo implantation and is absent in some infertile strains of mice.

METHODS

To investigate the process of uterine closure a ferritin-based tracer, used as a marker of endocytosis, was injected into the uterine lumen on day 5 of pregnancy when closure occurs.

RESULTS

Unexpectedly, luminal epithelial uptake of tracer was minimal on day 5 of pregnancy discrediting endocytosis as the induction method of uterine closure. In contrast, ferritin was found deep in the stromal portion of the endometrium in pre-pregnant animals.

CONCLUSIONS

We have shown for the first time that uterine closure is not induced by luminal epithelial cell driven endocytosis. Another novel finding of this study was the passage of the tracer ferritin up to 15 cells deep into the endometrium suggesting an as yet unstudied mechanism by which information can be transported from the uterine lumen to the underlying stroma.