LnCRNAs in the Regulation of Endometrial Receptivity for Embryo Implantation.

The development of endometrial receptivity is crucial for successful embryo implantation and the initiation of pregnancy. Understanding the molecular regulatory processes that transform the endometrium into a receptive phase is essential for enhancing implantation rates in fertility treatments, such as in vitro fertilization (IVF). Long non-coding RNAs (lncRNAs) play a pivotal role as gene regulators and have been examined in the endometrium. This review offers current insights into the role of lncRNAs in regulating endometrial receptivity. Considering the significant variation in endometrial remodeling among species, we summarize the key events in the human endometrial cycle and discuss the identified lncRNAs in both humans and other species, which may play a crucial role in establishing receptivity. Notably, there are 742 lncRNAs in humans and 4438 lncRNAs that have the potential to modulate endometrial receptivity. Additionally, lncRNAs regulating matrix metalloproteinases (MMPs) and Let-7 have been observed in both species. Future investigations should explore the potential of lncRNAs as therapeutic targets and/or biomarkers for diagnosing and improving endometrial receptivity in human fertility therapy.

The in vitro effects of n-3 fatty acids on immune response regulation of bovine ex vivo endometrial explants / Os efeitos in vitro dos ácidos graxos n-3 na regulação da resposta imune de explantes endometriais bovinos ex vivo

Fatty acids are considered metabolic intermediaries, although new facts indicate they also work as signaling molecules with different roles in the immune response. Based on that, in this study, we investigated the anti-inflammatory effects of n-3 polyunsaturated fatty acids (PUFAs) as eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and α-linolenic acid (LNA) in ex vivo bovine endometrial explants. For this, two groups were formed: (1) LPS-challenged and (2) control, both to evaluate the accumulation of proinflammatory cytokines as interleukin 1ß (IL1B) and interleukin 6 (IL6). To develop the study, bovine female reproductive tracts from non-pregnant Angus heifers without evidence of reproductive diseases were selected. Endometrial explants were processed and treated for 24 h with EPA, DHA, and LNA in five different concentrations (0µM, 50µM, 100 µM, 200µM and 400 µM) and then, challenged with LPS for 24 h. Supernatants were collected to evaluate the concentration of IL1B and IL6 by ELISA. Explants treated with EPA from control groups reduced the concentrations of ILB (200µM) and IL6 (400 µM), and IL6 (50 µM; 100 µM) from the LPS-challenged group. DHA decreased the accumulation of IL1B and IL6 at 200 µM on explants from the LPS-challenged group, and 200 µM reduced IL6 from the control group. In contrast, explants treated with LNA only reduced the accumulation of IL1B to 400µM (from both groups). In conclusion, the EPA acid is the best anti-inflammatory option to decrease the concentration of both pro-inflammatory cytokines (IL1B and IL6) from LPS-challenged and control groups in bovine endometrial explants; while LNA evidence to be the last option to promote an anti-inflammatory response.(AU)

Os ácidos graxos são considerados intermediários metabólicos, embora novos fatos indiquem que eles também atuem como moléculas sinalizadoras com diferentes papéis na resposta imune. Dessa forma, este estudo investigou os efeitos anti-inflamatórios de ácidos graxos poliinsaturados n-3 (PUFAs) como ácido eicosapentaenóico (EPA), ácido docosahexaenóico (DHA) e ácido α-linolênico (LNA) em explantes endometriais ex vivo de bovinos. Para tal, o experimento foi divido em dois grupos: (1) Desafiado-LPS e (2) Controle, para que então pudesse avaliar o acúmulo de citocinas pró-inflamatórias como interleucina 1ß (IL1B) e interleucina 6 (IL6). Foram selecionados tratos reprodutivos de fêmeas bovinas de novilhas Angus não prenhes sem evidência de doenças reprodutivas. Explantes endometriais foram processados e tratados por 24h com EPA, DHA e LNA em cinco concentrações diferentes (0µM, 50µM, 100 µM, 200µM e 400 µM) e, em seguida, desafiados com LPS por mais 24h. Os sobrenadantes foram colhidos para avaliar a concentração de IL1B e IL6 pelo teste de ELISA. Os explantes tratados com EPA dos grupos de controle reduziram as concentrações de ILB (200 µM) e IL6 (400 µM) e no grupo desafiado com LPS houve redução das concentrações de IL6 (50 µM; 100 µM). Nos explantes do grupo desafiado com LPS, o DHA diminuiu o acúmulo de IL1B e IL6 nas concentrações de 200 µM, e no grupo controle reduziu IL6 nas concentrações de 200 µM, enquanto os explantes tratados com LNA reduziram apenas o acúmulo de IL1B a 400 µM (de ambos os grupos). Em conclusão, o ácido EPA provou ser a melhor opção anti-inflamatória para diminuir a concentração de ambas as citocinas pró-inflamatórias (IL1B e IL6) de grupos desafiados com LPS e controle em explantes endometriais bovinos; enquanto o LNA evidencia ser a opção menos viável para promover uma resposta anti-inflamatória.(AU)

The role of progesterone receptor membrane component (PGRMC) in the endometrium.

PGRMC is a non-classical receptor that mediates the non-genomic responses to progesterone and is distributed in different subcellular compartments. PGRMC belongs to the membrane-associated progesterone receptor (MAPR) family. Two PGRMC subtypes (PGRMC1 and PGRMC2) have been characterized, and both are expressed in the human endometrium. PGRMC expression is differentially regulated during the menstrual cycle in the human endometrium. Although PGRMC1 is predominantly expressed in the proliferative phase and PGRMC2 in the secretory phase, this expression changes in pathologies such as endometriosis, in which PGRMC2 expression considerably decreases, promoting progesterone resistance. In endometrial cancer, PGRMC1 is overexpressed, its activation induces tumors growth, and confers chemoresistance in the presence of progesterone. Thus, PGRMCs play a key role in progesterone actions in the endometrium.

Endometrial preparation for women undergoing embryo transfer with frozen embryos or embryos derived from donor oocytes.

BACKGROUND: A frozen embryo transfer (FET) cycle is when one or more embryos (frozen during a previous treatment cycle) are thawed and transferred to the uterus. Some women undergo fresh embryo transfer (ET) cycles with embryos derived from donated oocytes. In both situations, the endometrium is primed with oestrogen and progestogen in different doses and routes of administration. OBJECTIVES: To evaluate the most effective endometrial preparation for women undergoing transfer with frozen embryos or embryos from donor oocytes with regard to the subsequent live birth rate (LBR). SEARCH METHODS: The Cochrane Gynaecology and Fertility Group trials register, CENTRAL, MEDLINE, Embase, PsycINFO, LILACS, trials registers and abstracts of reproductive societies' meetings were searched in June 2020 together with reference checking and contact with study authors and experts in the field to identify additional studies. SELECTION CRITERIA: Randomised controlled trials (RCTs) evaluating endometrial preparation in women undergoing fresh donor cycles and frozen embryo transfers. DATA COLLECTION AND ANALYSIS: We used standard methodological procedures recommended by Cochrane. We analysed all available interventions versus placebo, no treatment, or between each other. The primary review outcome was live birth rate. Secondary outcomes were clinical and multiple pregnancy, miscarriage, cycle cancellation, endometrial thickness and adverse effects. MAIN RESULTS: Thirty-one RCTs (5426 women) were included. Evidence was moderate to very low-quality: the main limitations were serious risk of bias due to poor reporting of methods, and serious imprecision. Stimulated versus programmed cycle We are uncertain whether a letrozole-stimulated cycle compared to a programmed cycle, for endometrial preparation, improves LBR (odds ratio (OR) 1.26, 95% confidence interval (CI) 0.49 to 3.26; 100 participants; one study; very low-quality evidence). Stimulating with follicle stimulating hormone (FSH), letrozole or clomiphene citrate may improve clinical pregnancy rate (CPR) (OR 1.63, 95% CI 1.12 to 2.38; 656 participants; five studies; I2 = 11%; low-quality evidence). We are uncertain if they reduce miscarriage rate (MR) (OR 0.79, 95% CI 0.36 to 1.71; 355 participants; three studies; I2 = 0%; very low-quality evidence). Endometrial thickness (ET) may be reduced with clomiphene citrate (mean difference(MD) -1.04, 95% CI -1.59 to -0.49; 92 participants; one study; low-quality evidence). Other outcomes were not reported. Natural versus programmed cycle We are uncertain of the effect from a natural versus programmed cycle for LBR (OR 0.97, 95% CI 0.74 to 1.28; 1285 participants; four studies; I2 = 0%; very low-quality evidence) and CPR (OR 0.79, 95% CI 0.62 to 1.01; 1249 participants; five studies; I2 = 60%; very low-quality evidence), while a natural cycle probably reduces the cycle cancellation rate (CCR) (OR 0.60, 95% CI 0.44 to 0.82; 734 participants; one study; moderate-quality evidence). We are uncertain of the effect on MR and ET. No study reported other outcomes. Transdermal versus oral oestrogens From low-quality evidence we are uncertain of the effect transdermal compared to oral oestrogens has on CPR (OR 0.86, 95% CI 0.59 to 1.25; 504 participants; three studies; I2 = 58%) or MR (OR 0.55, 95% CI 0.27 to 1.09; 414 participants; two studies; I2 = 0%). Other outcomes were not reported. Day of starting administration of progestogen When doing a fresh ET using donated oocytes in a synchronised cycle starting progestogen on the day of oocyte pick-up (OPU) or the day after OPU, in comparison with recipients that start progestogen the day prior to OPU, probably increases the CPR (OR 1.87, 95% CI 1.13 to 3.08; 282 participants; one study, moderate-quality evidence). We are uncertain of the effect on multiple pregnancy rate (MPR) or MR. It probably reduces the CCR (OR 0.28, 95% CI 0.11 to 0.74; 282 participants; one study; moderate-quality evidence). No study reported other outcomes. Gonadotropin-releasing hormone (GnRH) agonist versus control A cycle with GnRH agonist compared to without may improve LBR (OR 2.62, 95% CI 1.19 to 5.78; 234 participants; one study; low-quality evidence). From low-quality evidence we are uncertain of the effect on CPR (OR 1.08, 95% CI 0.82 to 1.43; 1289 participants; eight studies; I2 = 20%), MR (OR 0.85, 95% CI 0.36 to 2.00; 828 participants; four studies; I2 = 0%), CCR (OR 0.49, 95% CI 0.21 to 1.17; 530 participants; two studies; I2 = 0%) and ET (MD -0.08, 95% CI -0.33 to 0.16; 697 participants; four studies; I2 = 4%). No study reported other outcomes. Among different GnRH agonists From very low-quality evidence we are uncertain if cycles among different GnRH agonists improves CPR or MR. No study reported other outcomes. GnRH agonists versus GnRH antagonists GnRH antagonists compared to agonists probably improves CPR (OR 0.62, 95% CI 0.42 to 0.90; 473 participants; one study; moderate-quality evidence). We are uncertain of the effect on MR and MPR. No study reported other outcomes. Aspirin versus control From very low-quality evidence we are uncertain whether a cycle with aspirin versus without improves LBR, CPR, or ET. Steroids versus control From very low-quality evidence we are uncertain whether a cycle with steroids compared to without improves LBR, CPR or MR. No study reported other outcomes. AUTHORS' CONCLUSIONS: There is insufficient evidence on the use of any particular intervention for endometrial preparation in women undergoing fresh donor cycles and frozen embryo transfers. In frozen embryo transfers, low-quality evidence showed that clinical pregnancy rates may be improved in a stimulated cycle compared to a programmed one, and we are uncertain of the effect when comparing a programmed cycle to a natural cycle. Cycle cancellation rates are probably reduced in a natural cycle. Although administering a GnRH agonist, compared to without, may improve live birth rates, clinical pregnancy rates will probably be improved in a GnRH antagonist cycle over an agonist cycle. In fresh synchronised oocyte donor cycles, the clinical pregnancy rate is probably improved and cycle cancellation rates are probably reduced when starting progestogen the day of or day after donor oocyte retrieval. Adequately powered studies are needed to evaluate each treatment more accurately.

Decidualization Process Induces Maternal Monocytes to Tolerogenic IL-10-Producing Dendritic Cells (DC-10).

Decidualization is a process that involves phenotypic and functional changes of endometrial stromal cells to sustain endometrial receptivity and the participation of immunoregulatory factors to maintain immune homeostasis. In this context, tolerogenic dendritic cells (DCs) can induce regulatory T cells, which are essential to manage the pro- to anti-inflammatory transition during embryo implantation. Recently, Myeloid Regulatory Cells (MRCs) were proposed as immunosuppressants and tolerance-inducer cells, including the DC-10 subset. This novel and distinctive subset has the ability to produce IL-10 and to induce type 1 regulatory T cells (Tr1) through an HLA-G pathway. Here we focus on the impact of the decidualization process in conditioning peripheral monocytes to MRCs and the DC-10 subset, and their ability to induce regulatory T cells. An in vitro model of decidualization with the human endometrial stromal cell line (HESC), decidualized by medroxyprogesterone and dibutyryl-cAMP was used. Monocytes isolated from peripheral blood mononuclear cells from healthy women were cultured with rhGM-CSF + rhIL-4 and then, the effect of conditioned media from decidualized (Dec-CM) and non-decidualized cells (Non-dec-CM) was tested on monocyte cultures. We found that Dec-CM inhibited the differentiation to the CD1a+CD14- immature DC profile in a concentration-dependent manner. Dec-CM also significantly increased the frequency of CD83+CD86low and HLA-DR+ cells in the monocyte-derived culture. These markers, associated with the increased production of IL-10, are consistent with a MRCs tolerogenic profile. Interestingly, Dec-CM treatment displayed a higher expression of the characteristic markers of the tolerogenic DC-10 subset, HLA-G and ILT2/CD85j; while this modulation was not observed in cultures treated with Non-dec-CM. Moreover, when monocyte cultures with Dec-CM were challenged with LPS, they sustained a higher IL-10 production and prevented the increase of CD83, CD86, IL-12p70, and TNF-α expression. Finally, the DC-10 subset was able to induce a CD4+HLA-G+ regulatory T cells subset. These results suggest that the decidualization process might induce different subsets of MRCs, like DC-10, able to induce regulatory T cells as a novel CD4+HLA-G+ subset which might play an immunoregulatory role in embryo implantation.

VIP conditions human endometrial receptivity by privileging endoplasmic reticulum stress through ATF6α pathway.

Endometrial stromal cells undergo endoplasmic reticulum (ER) stress and unfolded protein response (UPR) during the decidualization linked with the inflammation and angiogenesis processes. Considering VIP (vasoactive intestinal peptide) induces the decidualization program, we studied whether modulates the ER/UPR pathways to condition both processes for embryo implantation. When Human Endometrial Stromal Cell line (HESC) were decidualized by VIP we observed an increased expression of ATF6α, an ER stress-sensor, and UPR markers, associated with an increase in IL-1ß production. Moreover, AEBSF (ATF6α -inhibitor pathway) prevented this effect and decreased the expansion index in the in vitro model of implantation. VIP-decidualized cells also favor angiogenesis accompanied by a strong downregulation in thrombospondin-1. Finally, ATF6α, VIP and VPAC2-receptor expression were reduced in endometrial biopsies from women with recurrent implantation failures in comparison with fertile. In conclusion, VIP privileged ATF6α-pathway associated with a sterile inflammatory response and angiogenesis that might condition endometrial receptivity.

Effects of recombinant bovine somatotropin on pregnancy per artificial insemination, corpus luteum cellular composition and endometrial gland morphometry in beef cattle.

The aim of this research was to evaluate the effect of recombinant bovine somatotropin (bST) on pregnancy per artificial insemination (P/AI), cellular composition of the corpus luteum (CL) and endometrial gland morphometry. In Experiment 1, Nelore cows (n = 587) received a fixed-time artificial insemination (FTAI) protocol and, at insemination, received 0, 250 or 500 mg of bST subcutaneously (SC). In Experiment 2, Nelore cows (n = 243) received 0 or 500 mg of bST, SC, on D7 (D0 = day of FTAI). Blood samples were collected on D7 and D16 to measure progesterone (P4) concentrations. In Experiments 1 and 2, pregnancy diagnosis was performed 30 days after FTAI. In Experiment 3, Nelore heifers (n = 20) received a FTAI protocol, but were not inseminated, and on D0 (ovulation day), they received 0 (bST 0; n = 9) or 500 mg of bST (bST 500; n = 11), SC. The heifers were slaughtered on D15 (D0 = ovulation day), at which time the CL was evaluated for diameter, weight, a percentage of large (LLC) and small (SLC) luteal cells, and the concentration of progesterone in plasma measured. The number, perimeter and area of superficial and deep endometrial glands were evaluated. There was no difference in P/AI when bST was applied on D0 and D7. In Experiment 1, P/AI did not differ among treatments, with 59.28% (115/194), 58.38% (115/197) and 65.82% (129/196) for the bST 0, 250 and 500 treatments, respectively. In Experiment 2, P/AI did not differ between treatments, with 57.3% (71/124) and 60.5% (62/119) for the bST 0 and 500 treatments, respectively. Plasma progesterone concentrations on D16 was greater in the bST 500 (11.63 ±â€¯0.84 ng/mL) than bST 0 (9.83 ±â€¯0.88 ng/mL). In Experiment 3, there was no difference in ovarian diameter and weight, CL diameter, percentage of SLC, P4 concentrations and endometrial gland morphology. Heifers in the bST 500 treatment had heavier CL (3.11 ±â€¯0.32 vs. 2.25 ±â€¯0.20 g); however, the bST 0 treatment heifers had a greater percentage of LLC than did the bST 500 treatment (13.72 ±â€¯1.16% vs. 8.60 ±â€¯1.52). It was concluded that the doses of bST used in this study do not increase P/AI; however, they do cause changes in P4 concentration and the cellular composition of the CL.

Ultrasound monitoring of the uterus and ovaries of dominant and subordinate females of yellow-breasted capuchin (Sapajus xanthosternos) and robust tufted capuchin (Sapajus robustus) in captive colonies during the ovarian cycle and anestrus periods / Acompanhamento ultrassonográfico do útero e ovários de fêmeas dominantes e subordinadas de macacos-prego-do-peito-amarelo (Sapajus xanthosternos) e macacos-prego-de-crista (Sapajus robustus) em colônias cativas, durante o ciclo ovariano e períodos de anestro

The yellow-breasted capuchin (Sapajus xanthosternos) and robust tufted capuchin (Sapajus robustus) are endangered species due to destruction of their natural habitat and predatory chase. However, it is still necessary to elucidate some details of their reproductive physiology in order to obtain better indices in the assisted reproduction of these species. This study aimed to evaluate the ovarian cycle of 13 dominant and subordinate females of S. xanthosternos (n=8) and S. robustus (n=5) using sagittal and transversally scanned ultrasound of their uterus and ovaries. Sonograms were performed every seven days for two months. The ovarian cycle phase and anestrous condition were confirmed by colpocytology. Our results showed different uterine parameters (craniocaudal diameter, dorso-ventral diameter, and transverse diameter) (P<0.05) between anestrous subordinate females and other ovarian cycle phases and social classes. The mean of uterine volume was higher in dominant females than subordinate females in all cycle phases (P<0.05), except in follicular phase. During anestrus, endometrial width was smaller in subordinate females than in dominant females (P<0.05). Subordinate females showed differences in endometrial measures (P<0.05) between anestrous period and follicular and luteal periods. Ovarian measures in dominant females were higher than in subordinate females only during anestrus (P<0.05). In the subordinate females, ovarian parameters were different (P<0.05) between anestrus and follicular and luteal phases. Dominant females showed higher volume of right ovary compared to volume of the left ovary during anestrus and follicular phase (P<0.05). Follicles and corpus luteum were distinguished by ultrasonography in most exams (86.11%). During anestrus, measurable ovarian structures were not observed in both ovaries in dominant and subordinate females. In conclusion, the methodology used in this study allowed to evaluate the ovarian cycle in S. xanthosternos e S. robustus females and that cycle phase/anestrus and social class of the female influenced the size of the uterus and ovaries.(AU)

O macaco-prego-do-peito-amarelo (Sapajus xanthosternos) e o macaco-prego-de-crista (Sapajus robustus) encontram-se em risco de extinção devido a destruição do seu habitat e a caça predatória. Porém, ainda necessita-se elucidar alguns detalhes de sua fisiologia reprodutiva, para obterem-se melhores índices por meio de reprodução assistida. Sendo assim, o objetivo deste trabalho foi acompanhar o ciclo ovariano de 13 fêmeas dominantes e subordinadas de S. xanthosternos (n=8) e S. robustus (n=5) por meio de cortes ultrassonográficos sagitais e transversais do útero e dos ovários. Estas fêmeas foram examinadas uma vez por semana durante dois meses. A fase do ciclo ovariano/anestro foi confirmada pela colpocitologia. Os resultados da pesquisa demonstrou diferença significativa (P<0,05) relacionada ao diâmetro crânio-caudal, diâmetro dorso-ventral e diâmetro transversal entre as fêmeas subordinadas em anestro com todas as outras fases do ciclo ovariano e classes sociais. A média do volume uterino foi maior nas fêmeas dominantes que nas subordinadas em todas as fases do ciclo (P<0,05) a exceção da fase folicular. A largura endometrial, durante o período de anestro, foi menor nas fêmeas subordinadas quando comparada às dominantes (P<0,05). Nas fêmeas subordinadas, houve diferenças (P<0,05) nas mensurações endometriais entre o período de anestro e das fases folicular e lútea. Quanto aos ovários, as médias das medidas observadas nas fêmeas dominantes foram superiores as das subordinadas durante o anestro (P<0,05). As médias das medidas das variáveis ovarianas das fêmeas subordinadas apresentaram diferenças entre o anestro e as fases folicular e lútea (P<0,05). Nas fêmeas dominantes o volume do ovário direito foi maior que o do ovário esquerdo durante o anestro e na fase folicular (P<0,05). Folículos e corpos lúteos foram diferenciados pela ultrassonografia na maioria das coletas (86,11%). Durante o anestro não foram observadas estruturas ovarianas mensuráveis nos ovários em ambas as classes sociais. Concluiu-se que a metodologia empregada neste estudo permitiu o acompanhamento do ciclo ovariano das fêmeas S. xanthosternos e S. robustus e que as fases do ciclo/anestro e a classe social das fêmeas influenciaram as medidas do útero e ovários.(AU)

Interacción endometrio trofoblasto, en la implantación humana: revisión de la literatura / Endometrium-trophoblast interaction in human implantation: review of literature

Un embarazo exitoso requiere de una serie de interacciones mediadas por factores hormonales, moleculares y fenómenos de inmunomodulación. Una de estas interacciones es la que ocurre entre el endometrio y el blastocito, previo y durante el proceso de implantación. El objetivo de esta revisión bibliográfica es complementar lo descrito en la literatura clásica de embriología humana sobre interacción de endometrio-blastocito. La búsqueda bibliográfica se realizó en la base de datos MEDLINE usando los términos en inglés "implantation", "endometrium" y "embryo"; además se realizó una búsqueda manual, que incluyó artículos de revistas no indexadas, libros de texto y atlas. Se consideraron criterios de inclusión y exclusión para la selección de los artículos y otros recursos bibliográficos. Entre los criterios de inclusión se consideraron estudios realizados en humanos, artículos de revisión y experimentación, publicados en los últimos 5 años. Como criterios de exclusión se consideraron artículos que utilizaran animales, estudios sobre fertilidad in vitro, patologías asociadas y artículos no relacionados al tema. Una vez completada la selección, se examinaron los textos completos, en los cuales se aplicaron nuevamente los criterios de exclusión. La búsqueda arrojó un total de 560 artículos, cuyo análisis de los títulos y resúmenes resultó en 475 trabajos excluidos, a partir de los diferentes criterios de exclusión antes descritos. Por lo tanto, se obtuvieron 85 artículos, en los cuales se realizó el análisis del texto completo. De estos artículos, se obtuvieron un total de 34 estudios y los contenidos seleccionados en esta revisión fueron: Endometrio, Interacción endometrio trofoblasto, Aposición, Adhesión y Migración-Invasión. Durante la implantación se genera una interacción entre el endometrio y el trofoblasto, con la participación de moléculas reguladoras de proliferación y diferenciación, como factores hormonales, moleculares y de expresión génica. Sin embargo, los mecanismos específicos de acción e interacción deben continuar siendo investigados, para responder interrogantes en el ámbito del crecimiento y desarrollo humano.

A successful pregnancy requires a series of interactions, mediated by hormonal, molecular and immunomodulation phenomena. One of these interactions is between the endometrium and the blastocyst, before and during the implantation process. The objective of this literature review is to complement what is described in the classic human embryology literature on endometrial-blastocyst interaction. The bibliographic search was carried out in the MEDLINE database using the terms "implantation", "endometrium" and "embryo", and a manual search was carried out, which included articles from non-indexed journals, textbooks and atlases. Inclusion and exclusion criteria were considered for the selection of articles and other bibliographic resources, including human studies, review and experimentation articles, published in the last 5 years. Articles with animals as experimental subjects, in vitro fertility studies, associated pathologies and articles not related to the subject were excluded. When the selection was completed, the complete texts were examined, in which the exclusion criteria were applied again The search yielded a total of 560 articles, whose analysis of titles and abstracts resulted in 475 excluded works, in relation to different exclusion criteria described above. Therefore, 85 articles were obtained, in which the complete text analysis was performed. From these articles, a total of 34 studies were obtained and the contents selected in this review were: Endometrium, Endometrium trophoblast, Aposition, Adhesion and Migration-Invasion. During the implantation, aninteraction between the endometrium and the trophoblast is generated, with the participation of regulatory molecules of proliferation and differentiation, such as hormonal, molecular and gene expression factors. However, the specific mechanisms of action and interaction must continue to be investigated, to answer questions in the field of human growth and development.

Ultrastructural and histological characteristics of the equine endometrium at day 5 post ovulation.

Rapid endometrial adaptations occur with the embryo entering the uterus to create a receptive uterine environment, which is essential for the conceptus' development. The aim of this study was to demonstrate ultrastructural and histological changes of the endometrium at day 5 after ovulation in cyclic and inseminated mares. Mares were daily examined by transrectal palpation and ultrasonographic examination of the reproductive tract until ovulation was detected. In the first cycle, endometrial biopsies from 10 cyclic mares (Cyclic group) were collected on day 5 post-ovulation. In the second cycle, the same mares were inseminated with fresh semen from a fertile stallion (Inseminated group). Intrauterine biopsies were collected on day 5 post-ovulation, and according to sampling moment, inseminated mares were subdivided into two subgroups, those sampled at day 5-5.5 (n = 5) and those sampled at day 5.5-6 (n = 5). Biopsy samples were analyzed through scanning electron microscopy and light microscopy. Inseminated group presented an increase in glandular diameter, decrease in ciliated cell population, and an increase in lymphocyte population, compared to Cyclic group. No differences were observed between both experimental groups in number of micro-ciliated polygonal cells, percentage of flat or protruded cells in the epithelium, amount of secretion over the epithelium, glandular density, glandular luminal diameter, height of the glandular epithelium, amount of intraglandular secretion, blood vessel diameter and number of eosinophils and neutrophils. No differences in any of the variables were detected between subgroups from inseminated mares. These facts lead to the hypothesis that there is some sort of signaling to prepare and adapt the uterus to maintain pregnancy even before embryo arrival. There is also evidence to support an alternative hypothesis suggesting that all of the above mentioned are inflammatory events, resulting from a previous inflammation due to residual seminal effects. The results here presented lead to the conclusion that significant ultrastructural and histological changes of the endometrium occur on day 5 post ovulation in inseminated mares.

Luteal vascularity and embryo dynamics in mares during early gestation: Effect of age and endometrial degeneration.

The present study characterized the luteal status and the dynamic of the conceptus during the first 20 days of gestation in mares with different ages and degrees of endometrial degeneration. Total area of the corpus luteum (CL), luteal vascularity, CL area with blood signals, progesterone concentrations (P4), embryonic vesicle diameter, number of embryonic location changes, embryonic fixation position and uterine contractility were evaluated. In Experiment 1, mares ≤6 years of age (Young group, 5.6 ± 0.2 years, n = 7 mares) and mares ≥15 years of age (Old group, 17.2 ± 0.9 years, n = 6 mares) were used to investigate the effect of age. In Experiment 2, the luteal and embryonic parameters were compared between mares with minimal (Mild group, endometrial category I, n = 9 mares) and severe (Severe group, endometrial category III, n = 7 mares) endometrial degeneration. The Old and Severe groups had greater (p ≤ 0.04) total CL area and reduced luteal vascularity (p ≤ 0.04) than the Young and Mild groups, respectively. However, P4 levels and CL area with blood signals were similar (p ≥ 0.8) between the groups. A negative effect of age (p < 0.01), but not of endometrial degeneration (p = 0.6), was found for the embryonic vesicle diameter. The conceptus mobility was high (p > 0.1) until day 14 of gestation in the Severe group, while a reduced number of changes of the embryo location was detected earlier (p < 0.05) in the Old group. In conclusion, the newly formed CL of aged mares and mares with severe endometrial degeneration suffered a structural remodelling to safeguard the local blood supply and the continuous P4 output during early gestation. Moreover, an earlier reduction of the embryonic mobility and a delayed development of the conceptus were associated with advanced age, regardless of the degree of endometrial degeneration.

Métodos de coleta de amostra para exame de citologia endometrial em éguas com endometrite / Sample collection methods for endometrial cytology examination in mares with endometritis

A endometrite é definida como uma inflamação do endométrio, podendo ser aguda ou crônica, infecciosa ou não infecciosa. Essa afecção é de grande importância econômica na medicina veterinária, podendo resultar em morte embrionária, aborto e até tornar a égua infértil, sendo uma das afecções que mais comprometem a sanidade uterina, colocando em risco os índices de prenhez obtidos pós-cobertura, pós-inseminação, e pós-inovulação de embriões. Existem diversos métodos para diagnóstico e o mais utilizado a campo é a citologia endometrial/uterina. Também existem algumas formas de coleta de amostra para análise laboratorial pela citologia, tais como: escova ginecológica, swab uterino guiado por mandril metálico ou plástico descartável e lavado uterino de baixo volume, seguido de sedimentação ou centrifugação podendo ser complementada por citocentrifugação. O diagnóstico pela citologia endometrial por meio da técnica da escova ginecológica é a mais utilizada entre os médicos veterinários, pois trata-se de um método prático para execução e rápido quanto à obtenção dos resultados sobre a presença ou não da endometrite, facilitando a conduta terapêutica quanto à utilização das éguas para reprodução ou descarte. Objetivou-se com esse estudo citaras formas de diagnóstico da endometrite em éguas, enfatizando a citologia endometrial e técnicas para obtenção de amostra, identificando a técnica mais indicada por diversos autores.

Endometritis is defined as an inflammation of the endometrium, which may be acute or chronic, infectious or noninfectious. This condition is of great economic importance in veterinary medicine, and may result in embryonic death, abortion and even render the mare infertile, being one of the conditions that most compromise uterine health, putting at risk the pregnancy rates obtained post-coverage, postinsemination, and post-embryo transfer. There are several methods for diagnosis and the most used in the field is endometrial/uterine cytology. There are also some forms of sample collection for laboratory analysis by cytology, such as: gynecological brush, uterine swab guided by metallic mandrel or disposable plastic and low volume uterine lavage, followed by sedimentation or centrifugation and may be complemented by cytocentrifugation. Diagnosis by endometrial cytology using the gynecological brush technique is the most used among Veterinary Practitioners, because it is a practical method to execute and fast to obtain the results in the presence of endometritis, facilitating the therapeutic conduct regarding the use of mares for breeding or discarding. The objective of this study was to cite the diagnostic methods of endometritis in mares, emphasizing endometrial cytology and its techniques for obtaining a sample, identifying the most indicated technique by several authors.

Métodos de coleta de amostra para exame de citologia endometrial em éguas com endometrite / Sample collection methods for endometrial cytology examination in mares with endometritis

A endometrite é definida como uma inflamação do endométrio, podendo ser aguda ou crônica, infecciosa ou não infecciosa. Essa afecção é de grande importância econômica na medicina veterinária, podendo resultar em morte embrionária, aborto e até tornar a égua infértil, sendo uma das afecções que mais comprometem a sanidade uterina, colocando em risco os índices de prenhez obtidos pós-cobertura, pós-inseminação, e pós-inovulação de embriões. Existem diversos métodos para diagnóstico e o mais utilizado a campo é a citologia endometrial/uterina. Também existem algumas formas de coleta de amostra para análise laboratorial pela citologia, tais como: escova ginecológica, swab uterino guiado por mandril metálico ou plástico descartável e lavado uterino de baixo volume, seguido de sedimentação ou centrifugação podendo ser complementada por citocentrifugação. O diagnóstico pela citologia endometrial por meio da técnica da escova ginecológica é a mais utilizada entre os médicos veterinários, pois trata-se de um método prático para execução e rápido quanto à obtenção dos resultados sobre a presença ou não da endometrite, facilitando a conduta terapêutica quanto à utilização das éguas para reprodução ou descarte. Objetivou-se com esse estudo citaras formas de diagnóstico da endometrite em éguas, enfatizando a citologia endometrial e técnicas para obtenção de amostra, identificando a técnica mais indicada por diversos autores.(AU)

Endometritis is defined as an inflammation of the endometrium, which may be acute or chronic, infectious or noninfectious. This condition is of great economic importance in veterinary medicine, and may result in embryonic death, abortion and even render the mare infertile, being one of the conditions that most compromise uterine health, putting at risk the pregnancy rates obtained post-coverage, postinsemination, and post-embryo transfer. There are several methods for diagnosis and the most used in the field is endometrial/uterine cytology. There are also some forms of sample collection for laboratory analysis by cytology, such as: gynecological brush, uterine swab guided by metallic mandrel or disposable plastic and low volume uterine lavage, followed by sedimentation or centrifugation and may be complemented by cytocentrifugation. Diagnosis by endometrial cytology using the gynecological brush technique is the most used among Veterinary Practitioners, because it is a practical method to execute and fast to obtain the results in the presence of endometritis, facilitating the therapeutic conduct regarding the use of mares for breeding or discarding. The objective of this study was to cite the diagnostic methods of endometritis in mares, emphasizing endometrial cytology and its techniques for obtaining a sample, identifying the most indicated technique by several authors.(AU)

Intramammary infusion of lipopolysaccharide promotes inflammation and alters endometrial gene expression in lactating Holstein cows.

The objective of the current study was to evaluate the effects of 2 intramammary infusions of lipopolysaccharide (LPS) on inflammatory and reproductive parameters and endometrial gene expression of lactating Holstein cows. At 35 ± 7 d in milk, 20 cows were submitted to a Double Ovsynch program and randomly assigned to control (n = 11) and LPS (n = 9) treatments. Cows from the LPS treatment received 2 intramammary infusions of 25 µg of LPS after morning milking on d 5 and 10 post-AI, whereas control cows were infused with only saline. Blood samples were taken and ultrasound scanning of the ovaries was performed during the entire study before and after AI to determine haptoglobin, tumor necrosis factor-α, and progesterone concentrations as well as response to the hormonal protocol and corpus luteum diameter. Milk yield was evaluated and samples were taken for somatic cell count at 0, 10, 24, 34, and 96 h relative to each infusion. Rumen-reticular temperature was recorded using a rumen-reticular bolus logger and summarized hourly. On d 15 post-AI, uterine flushing for conceptus recovery and endometrial biopsies were performed. Samples of endometrium from cows with positive embryo recovery (control = 5; LPS = 6) were submitted to mRNA extraction and quantitative reverse-transcription PCR analysis of 96 target genes. Haptoglobin concentrations in plasma were greater for LPS treatment (control = 0.24 ± 0.07, LPS = 0.89 ± 0.06 optical density), but tumor necrosis factor-α concentrations were similar (control = 0.67 ± 0.11, LPS = 0.46 ± 0.11 ng/mL) between treatments. Lipopolysaccharide reduced milk yield after treatment (control = 34.3 ± 1.5, LPS = 29.4 ± 1.6 kg/d), whereas somatic cell count (log) was greater in LPS-treated cows until 34 h after infusions (control = 2.3 ± 0.1, LPS = 3.3 ± 0.1 cells/mL of milk). Rumen-reticular temperature of LPS cows was elevated between 5 and 10 h after each infusion compared with control cows (control = 39.5 ± 0.1, LPS = 40.1 ± 0.1°C). Progesterone concentration after AI was unaffected by treatment or pregnancy status as well as corpus luteum diameter and conceptus length on d 15. Lipopolysaccharide treatment altered the expression of 13 key genes in the endometrium (mostly upregulated), whereas another 17 tended to be modulated. Modified gene expression included genes related to immune response (PTX3 = 2.34-fold increase; IL6 = 3.42-fold increase; and TCN1 = 2.52-fold increase), adhesion molecules (CADM3 = 1.93-fold increase; MMP19 = 1.49-fold increase; EMMPRIN = 1.20-fold increase; SELL = 1.91-fold increase), Wnt signaling pathway (WNT2, FZD4, and FZD7, all <1.5-fold increase), and interferon-stimulated genes (BMP15 = 0.27-fold decrease; ISG15 = 2.17-fold increase, and MX2 = 2.23-fold increase). In summary, intramammary infusions of LPS were able to trigger an inflammatory response with no effect on corpus luteum diameter and concentration of progesterone in plasma. However, a limited but important set of modulations in the endometrium gene expression at d 15 of gestation was found.

Sphingolipid synthesis and role in uterine epithelia proliferation.

Sphingolipids are involved in the regulation of cell proliferation. It has been reported that diacylglycerol and sphingosine-1-phosphate generation, during the synthesis of phospho-sphingolipids, is necessary for both, G1-S transition of cell cycle during the sustained activation of protein kinase C in various cell models (MDCK, Saccharomyces and Entamoeba) and AKT pathway activation. During the estrous cycle of the rat, AKT signaling is the main pathway involved in the regulation of uterine cell proliferation. The aim of the present study was to investigate the role of sphingolipid synthesis during proliferation of uterine cells in the estrous cycle of the rat. On metestrus day, when both luminal and glandular uterine epithelia present the maximal BrdU-labeled cells (S phase cells), there was an increase in the relative abundance of total sphingomyelins, as compared to estrus day. Myriocin, a sphingolipid synthesis inhibitor administered on estrus day, before the new cell cycle of epithelial cells is initiated, decreased the abundance of sphingomyelin, accompanied by proliferation arrest in uterine epithelial cells on metestrus day. In order to study the sphingolipid signaling pathway affected by myriocin, we evaluated the activation of the PKC-AKT-GSK3b-Cyclin D3 pathway. We observed that total and phosphorylated protein kinase C diminished in uterine epithelial cells of myriocin treated animals. Interestingly, cyclin D3 nuclear localization was blocked by myriocin, concomitantly with a decrease in nuclear pRb expression. In conclusion, we demonstrate that sphingolipid synthesis and signaling are involved in uterine epithelial cell proliferation during the estrous cycle of the rat.

A single preovulatory administration of ulipristal acetate affects the decidualization process of the human endometrium during the receptive period of the menstrual cycle.

In order to get further information on the effects of ulipristal acetate (UPA) upon the process of decidualization of endometrium, a functional analysis of the differentially expressed genes in endometrium (DEG) from UPA treated-versus control-cycles of normal ovulatory women was performed. A list of 1183 endometrial DEG, from a previously published study by our group, was submitted to gene ontology, gene enrichment and ingenuity pathway analyses (IPA). This functional analysis showed that decidualization was a biological process overrepresented. Gene set enrichment analysis identified LIF, PRL, IL15 and STAT3 among the most down-regulated genes within the JAK STAT canonical pathway. IPA showed that decidualization of uterus was a bio-function predicted as inhibited by UPA. The results demonstrated that this selective progesterone receptor modulator, when administered during the periovulatory phase of the menstrual cycle, may affect the molecular mechanisms leading to endometrial decidualization in response to progesterone during the period of maximum embryo receptivity.

Platelet-rich plasma therapy and reproductive medicine.

Reports on clinical uses of platelet-rich plasma (PRP) have dramatically increased in the last decade. Indications for PRP therapy range from muscle and skeletal injuries to hair re-growth. More recently evidences have shown its positive effects in promoting endometrial and follicular growth and gestation in assisted reproduction cycles. We discuss the putative role of PRP on endometrial receptivity, with a brief history of its applications in research and clinical therapies. Despite its widespread uses in medicine, the mechanisms through which PRP exerts its regenerative effects are only postulated, not based on scientific data. There is an unmet need for advanced research to corroborate present findings in the clinical scenario.

Modeling early embryo-maternal interactions in vitro

Environmental conditions experienced during early embryonic development influence growth, metabolism, and gene expression of the embryo as well as the epigenetic profile of the offspring. The environment of the early embryo consists of the luminal fluid within the oviduct and uterus and the epithelial cells composing this fluid. Whether the embryo is able to shape its own microenvironment by interacting with the epithelial lining of the oviduct/uterus and which factors potentially interfere with or regulate these interactions remains to be elucidated. As early embryonic signals and the respective maternal responses are subtle and local events, it is challenging to study them in vivo. Therefore, adequate in vitro-models optimally mimicking the contact zone between the maternal reproductive tract and the early embryo are needed to a) elucidate basic mechanisms involved in early embryonic development and b) reduce the number of experimental animals used for such studies. Functional epithelial cells are generally defined by a polarized distribution of organelles and proteins. Proper polarization is tightly connected with physiological cell behavior and in vivo-like reactivity of the epithelium. Therefore, this review summarizes current strategies for in vitro preservation of epithelial cell polarity. It presents recent advances in 3D culture of female reproductive tract epithelia and embryo-epithelial cocultures. A special emphasis is set on compartmentalized culture systems, powerful tools for studying early embryo-maternal interactions in vitro. In such systems, cultured epithelial cells are manipulable from their basolateral as well as their apical cell pole, allowing concomitant application of embryonic as well as maternal effectors from the appropriate cellular compartment.(AU)

Modeling early embryo-maternal interactions in vitro

Environmental conditions experienced during early embryonic development influence growth, metabolism, and gene expression of the embryo as well as the epigenetic profile of the offspring. The environment of the early embryo consists of the luminal fluid within the oviduct and uterus and the epithelial cells composing this fluid. Whether the embryo is able to shape its own microenvironment by interacting with the epithelial lining of the oviduct/uterus and which factors potentially interfere with or regulate these interactions remains to be elucidated. As early embryonic signals and the respective maternal responses are subtle and local events, it is challenging to study them in vivo. Therefore, adequate in vitro-models optimally mimicking the contact zone between the maternal reproductive tract and the early embryo are needed to a) elucidate basic mechanisms involved in early embryonic development and b) reduce the number of experimental animals used for such studies. Functional epithelial cells are generally defined by a polarized distribution of organelles and proteins. Proper polarization is tightly connected with physiological cell behavior and in vivo-like reactivity of the epithelium. Therefore, this review summarizes current strategies for in vitro preservation of epithelial cell polarity. It presents recent advances in 3D culture of female reproductive tract epithelia and embryo-epithelial cocultures. A special emphasis is set on compartmentalized culture systems, powerful tools for studying early embryo-maternal interactions in vitro. In such systems, cultured epithelial cells are manipulable from their basolateral as well as their apical cell pole, allowing concomitant application of embryonic as well as maternal effectors from the appropriate cellular compartment.