Reproduction

In vitro culture of cryopreserved ovarian follicles has the potential to extend fertility options for young women seeking to preserve ovarian tissue prior to undergoing cancer treatments. Successful implementation of this strategy has been elusive and likely requires a more complete understanding of the microenvironment of the developing ovarian follicles, including ovarian oxygen concentrations. The oxygen tension within the reproductive tract plays a crucial role in follicular development and oocyte maturation. While in vitro culture systems often use atmospheric oxygen (21%), the native environment in vivo is significantly lower, ranging from 1.5% to 8.7%. This study aimed to investigate the effects of reduced oxygen tensions (3% and 5%) on follicle survival, growth, antrum formation, and hormone production in cultured secondary follicles from rhesus macaques (macaca mulata). A total of 300 follicles were isolated from 7 animals and cultured under three oxygen conditions: 3%, 5%, and 21% O2. Follicle survival and antrum formation were assessed weekly by microscopy and Kaplan-Meier survival analysis, while growth dynamics and hormone levels (estradiol, progesterone, AMH, and inhibin B) were monitored throughout the culture period. Results demonstrated that follicles cultured at 3% and 5% oxygen exhibited significantly higher survival rates and antrum formation compared to those cultured at 21% O2. No significant differences in survival were observed between the 3% and 5% oxygen groups. Growth dynamics revealed distinct patterns, with both low oxygen groups promoting more robust and sustained follicle growth, while atmospheric oxygen led to rapid degeneration. Hormonal analysis showed that follicles in 21% O2 had elevated early hormone production but exhibited reduced long-term viability. In contrast, 3% and 5% oxygen delayed hormone production, reflecting a more stable and sustained follicular environment. These findings underscore the importance of low oxygen tensions in mimicking the physiological conditions of the reproductive tract, improving follicular development, and supporting optimal hormonal function in vitro. This study suggests that further reducing oxygen levels to 3% may offer additional advantages for long-term follicle viability and function in reproductive technologies. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=71 SRC="FIGDIR/small/652505v1_ufig1.gif" ALT="Figure 1"> View larger version (17K): org.highwire.dtl.DTLVardef@11fcb62org.highwire.dtl.DTLVardef@61c0beorg.highwire.dtl.DTLVardef@1b5328forg.highwire.dtl.DTLVardef@10a7538_HPS_FORMAT_FIGEXP M_FIG C_FIG

The human endometrium undergoes cyclic, hormone-driven remodeling that establishes a transient window of receptivity required for embryo implantation, placentation, and maintenance of pregnancy. Decidualization of endometrial stromal cells is a central component of this process and can be induced in vitro using cAMP alone or in combination with ovarian steroid hormones (EPC: estradiol, progesterone, and cAMP). Although cAMP activates the core decidual transcriptional program, whether hormone supplementation induces a more physiologically relevant response remains unclear, particularly in 3D endometrial organoid (Endo-organoid) models which have emerged as a new alternative methodology (NAM). Here, we compared morphological and transcriptomic responses of human endometrial stromal cell-derived Endo-organoids undergoing decidualization induced by cAMP or EPC stimulation. EPC-treated Endo-organoids exhibited enhanced structural remodeling and more advanced morphological transformation compared with cAMP-treated organoids. RNA-seq analysis revealed substantial overlap in canonical decidual gene expression between the two conditions, but EPC induced broader transcriptional and pathway-level changes, including enrichment of metabolic, stress-response, and differentiation-related processes. Together, these findings demonstrate that while cAMP activates the core decidual program, EPC elicits a broader and more physiologically relevant decidualization response in 3D human Endo-organoids, providing guidance for optimizing Endo-organoids to study endometrial receptivity, implantation, and early pregnancy success.

BackgroundEndometriosis is a complex disease, and its pathophysiology is still unclear. Therefore, endometriosis animal models need to be carefully selected and examined to be useful for identification of novel therapies for women with endometriosis. In this study, we evaluated endometriosis-associated pain, and time- and estrogen-related development of endometriotic lesions after laparoscopic implantation of menstrual endometrium in a homologous mouse model for endometriosis. MethodsEndometriosis was induced by laparoscopic introduction of 10 menstrual endometrial tissue pieces into the peritoneum of ovariectomized recipient mice (59 estrogen-substituted; 59 estrogen-depleted). Sham animals (57 estrogen-substituted; 60 estrogen-depleted) received 10 pieces of perigonadal adipose tissue. The animals were sacrificed at 1, 2, 3, 4, 6 or 8 weeks after induction, the attached peritoneal implants localized and excised and immunohistochemically analyzed. Additionally, endometriosis-related pain was evaluated by measuring mechanical allodynia, thermal hyperalgesia, locomotor activity and anxiety-like behavior before and after tissue implantation. ResultsAt least one implant per mouse could be retrieved in 94% (111/118) of the endometrial tissue animals and in 78% (91/117) of the adipose tissue animals (p<0.001). Peritoneal implant take rate was significantly higher in endometrial tissue animals (2.5{+/-}1.4) compared to adipose tissue animals (1.6{+/-}1.5) (p<0.0001), regardless of estrogen supplementation and time of sacrifice. Hemosiderin could be observed more often (p<0.0001) in attached peritoneal implants of the endometrial tissue animals (67%, 68/101), compared to the adipose tissue animals (37%, 31/83). Ki67 staining showed a higher proliferation index in the attached peritoneal implants retrieved after one week, compared to the other time points of both endometrial tissue and adipose tissue animals. The behavioral test showed no significant difference in mechanical and thermal sensitivity, locomotor activity and anxiety-behavior between the menstrual endometrial tissue and adipose tissue implanted animals. Nevertheless, the estrogen-substituted animals showed decreased activity in the tests featuring thermal nociception and anxiety-like behavior, compared to the estrogen-depleted animals. Additionally, time after implantation showed to have a positive effect on thermal sensitivity, locomotor activity and anxiety-related behavior in all animals, as the mice became less sensitive to thermal stimuli, more active in the open field test and buried less marbles in the marble burying test. ConclusionThis study showed an increased attachment of menstrual endometrium compared to adipose tissue in the peritoneum when using laparoscopic induction. There was no apparent influence of estrogen on tissue attachment, proliferation or appearance. A decrease in cell proliferation in peritoneal implants occurred over time. Locomotor activity, anxiety-like behavior, and mechanical and thermal sensitivity of the animals was not affected after induction of endometriosis, regardless of the type of implanted tissue. Altogether, we showed that the current methodology used to induce endometriosis was not sufficient to develop endometriotic lesions that contained both stromal and epithelial cells. Moreover, the current methodology was not able to detect specific endometriosis-related pain. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=134 SRC="FIGDIR/small/583957v1_ufig1.gif" ALT="Figure 1"> View larger version (39K): org.highwire.dtl.DTLVardef@119ad34org.highwire.dtl.DTLVardef@ba5b8borg.highwire.dtl.DTLVardef@d020ccorg.highwire.dtl.DTLVardef@1941e8_HPS_FORMAT_FIGEXP M_FIG C_FIG

The cervix functions both as gatekeeper barrier to maintain pregnancy and virtually vanish for birth at term in mammals. The period of remodeling well-before term is characterized by an inflammatory process associated with reduced cell nuclei density and cross-linked collagen, as well as increased density of resident macrophages in cervix stroma. Contemporarily, progesterone (P4) is at or near peak concentrations in maternal circulation. The functional or actual loss of response to P4 is thought to drive the process that enhances uterine contractile activity for labor and parturition at term. The objective of the present study was to determine if actual or functional loss of P4 regulated cytomorphological characteristics associated with prepartum cervix ripening at term and with preterm birth. On day 16 of pregnancy. Ovaries were removed to eliminate the main source of P4 production and a silastic capsule implanted (with vehicle or P4, Ovx or Ovx+P4, respectively). Controls received a vehicle-filled capsule, while a P4 capsule was implanted into an addition group of Intact mice to ensure sustained concentrations throughout pregnancy (Intact+P4). Pups were born in controls at term (days 19-20 postbreeding), but deliveries were preterm in Ovx mice within 24h (day 17). In the Ovx+P4 group, births were delayed to term and post-term in most Intact+P4 mice with adverse pregnancy outcomes commonplace. Characteristics of cell nuclei and degradation of cross-linked collagen were advanced with preterm birth in Ovx mice compared to controls that gave birth by at term. Treatment of Ovx mice with P4 blocked preterm birth, but parturition was complicated by dystocia. In addition, P4 given to ovary-intact mice sustained peak pregnancy concentrations, but had minimal effects on cytoarchitecture of the prepartum cervix stroma except term birth was forestalled with dystocia and fetal morbidity. Density of resident macrophages in the cervix stroma in term Ovx+P4 mice was reduced along with area of macrophage stain versus postpartum controls. Thus, analyses of cervix cellular cytoarchitecture provided useful biomarkers of local inflammation to assessment the ripening process for preterm and term parturition. Collectively, findings suggest a functional loss of prepartum cervix responses to progesterone are part of a final common mechanism for parturition across mammals. SummaryLoss of response to progesterone withdrawal is associated with cervix ripening while some cytoarchitectural characteristics of remodeling are regulated to block preterm birth and dystocia at term

The rete ovarii (RO) is an epithelial structure that arises during fetal development in close proximity to the ovary and persists throughout adulthood in mice. However, the functional significance of the RO remains elusive, and it has been absent from recent discussions of female reproductive anatomy. The RO comprises three distinct regions: the intraovarian rete (IOR) within the ovary, the extraovarian rete (EOR) in the periovarian tissue, and the connecting rete (CR) linking the EOR and IOR. We hypothesize that the RO plays a pivotal role in maintaining ovarian homeostasis and responding to physiological changes. To uncover the nature and function of RO cells, we conducted transcriptome analysis, encompassing bulk, single-cell, and nucleus-level sequencing of both fetal and adult RO tissues using the Pax8-rtTA; Tre- H2B-GFP mouse line, where all RO regions express nuclear GFP. This study presents three datasets, which highlight RO-specific gene expression signatures and reveal differences in gene expression across the three RO regions during development and in adulthood. The integration and rigorous validation of these datasets will advance our understanding of the ROs roles in ovarian development, female maturation, and adult female fertility. Short narrativeThis study employs comprehensive bulk, single cell and single nucleus transcriptome analysis to uncover gene expression signatures of the fetal and adult rete ovarii (RO).

STUDY QUESTIONCan network modelling of single cell transcriptomic data identify cellular developmental trajectories of fallopian tube (FT) epithelium and reveal functional and pathological divergence from the endometrium? SUMMARY ANSWERA bidirectional secretory and ciliated differentiation trajectory was apparent from a novel OVGP1+ progenitor population of FT epithelial cells. A causal network model of whole transcriptome action in the FT and endometrium revealed specific functional divergence between secretory cells of these tissues. The network model reflected the latest ectopic pregnancy genome wide association study (GWAS), invoking MUC1 and other candidate genes in mature secretory cells for ectopic and eutopic implantation. WHAT IS KNOWN ALREADYThe fallopian tube forms the in vivo peri-conceptual environment, which has a significant impact on programming offspring health. The fallopian tube epithelium establishes this environment, however the epithelial cell types are poorly characterised in health and disease. STUDY DESIGN, SIZE, DURATIONPublicly available benign FT single cell RNA sequencing (scRNA-seq) samples from thirteen women across three studies were combined. Endometrial scRNA-seq samples from thirteen women from one study were used to demonstrate transcriptomic differences between the epithelia of the two tissues. Network models of transcriptomic action were constructed with hypergraphs. PARTICIPANTS/MATERIALS, SETTING, METHODSA meta-analysis of FT scRNA-seq samples was performed to identify epithelial populations. Differential gene expression assessed differences between fallopian tube and endometrial epithelial scRNA-seq data. Functional differences between secretory cells in the tissues were characterised using hypergraph models. To identify associations with ectopic pregnancy, expression quantitative trait loci (eQTLs) from a recent GWAS were mapped onto the network models. MAIN RESULTS AND THE ROLE OF CHANCEEpithelial cells (n=14,360) were clustered into 8 secretory and ciliated epithelial populations in the meta-analysis of 3 scRNA-seq datasets. A novel OVGP1+ epithelial progenitor cell was also identified, and its bi-directional differentiation to mature secretory or mature ciliated populations was mapped by RNA velocity analysis. This progenitor exhibited a high velocity magnitude (12.47) and low confidence (0.69), a combination strongly indicative of multipotent progenitor status. Comparing FT epithelial cells with endometrial epithelial cells revealed 5.3-fold fewer shared genes between FT and endometrial glandular secretory cells than between FT and endometrial ciliated cells, suggesting functional divergence of secretory cells along the reproductive tract. Hypergraphs were used to identify highly coordinated regions of the transcriptome robustly associated with functional gene networks. In the FT secretory cells, these networks were enriched for lipid (FDR<0.002) and immune (FDR<0.00007) related pathways. We mapped eQTLs from a GWAS meta-analysis of 7070 women with ectopic pregnancy over a range of significance (P = 1.68 x 10-21- 5.8 x 10-4) to the hypergraphs of FT and endometrium. Of the 22 genes present in the hypergraphs, 13 of these clustered as highly coordinated genes. This demonstrated the functional importance of MUC1 in the FT and endometrium, (GWAS Study P = 5.32x10-9) and identified additional genes (SLC7A2, CLDN1, GLS, PEX6, PLXNA4, NR2F1, CLGN, PGGHG, ANKRD36) implicated in ectopic pregnancy and eutopic pregnancy. LIMITATIONS, REASONS FOR CAUTIONThe sample size of reproductive age women was limited in previous studies, and though causal network modelling was used and previous mechanistic data supports candidate gene involvement, no in vitro or in vivo validation of candidate was performed. WIDER IMPLICATIONS OF THE FINDINGSThese findings consolidate the existing single cell transcriptomic datasets of the FT to provide a comprehensive understanding of epithelial populations and define functionally distinct secretory cells that contribute to the peri-conceptual environment of the FT. We further implicate the role of MUC1 and secretory cells in ectopic pregnancy and suggest future targets for investigating embryo implantation in the FT and endometrium.

Uterine luminal fluid (ULF) composition plays a major role in cell-to-cell communication between the receptive endometrium and an invading blastocyst. ULF is made up of secretions from the uterine glands and uterine epithelial cells (UEC). However, the cellular mechanisms regulating these exocytotic secretions are not yet understood. This study investigated the role of extracellular vesicles (EVs) during early pregnancy using Transmission Electron Microscopy (TEM). TEM analysis at time of fertilisation (TOF) Day 1 and at time of receptivity (TOR) Day 5.5 revealed EVs present, with an abundance at TOR. Exocytosis signalling in UECs, by SNARE proteins syntaxin 2 (syn2) and SNAP23, was also examined. Immunofluorescence microscopy showed both syn2 and SNAP23 to be present in the apical area of UECs at TOR. Western blot and immunofluorescence quantification revealed a significant increase in syn2 and SNAP23 at TOR compared to TOF. SNAP23 colocalization with apical actin showed SNAP23 was in the luminal space contributing to ULF. Overall, this data shows EVs, syn2 and SNAP23 (potential receptivity marker) are present in ULF and may together create a favourable microenvironment for blastocyst implantation. Summary statementDuring uterine receptivity SNAREs participate in the secretion of ULF. EVs and SNAP23 are present in the uterine luminal space during uterine receptivity. SNAP23 has the potential to be used as a receptivity marker.

This study investigates the short and long-term effects of IFNT and PAG on the transcriptome of endometrium and blood leukocytes. Holstein heifers received intrauterine infusions of one of the following treatments: 20 mL of a 200 g/mL bovine serum albumin solution (BSA; vehicle) from day 14 to 16 of the estrous cycle (BSA), vehicle + 10 g/mL of IFNT from day 14 to 16 (IFNT3), vehicle + 10 g/mL of IFNT from day 14 to 19 (IFNT6), and vehicle + 10 g/mL of IFNT from day 14 to 16 followed by vehicle + 10 g/mL of IFNT + 5 g/mL of PAG from day 17 to 19 (IFNT+PAG). RNA-seq analysis was performed in endometrial biopsies and blood leukocytes collected after treatments. Acute IFNT signaling in the endometrium (IFNT3 vs BSA), induced differentially expressed genes (DEG) associated with interferon activation, immune response, inflammation, cell death, and inhibited vesicle transport and extracellular matrix remodeling. Prolonged IFNT signaling (IFNT6 vs IFNT3) altered gene expression related to cell invasion, retinoic acid signaling, and embryo implantation. In contrast, PAG induced numerous DEG in blood leukocytes but only 4 DEG in the endometrium. In blood leukocytes, PAG stimulated genes involved in development and TGFB signaling while inhibiting interferon signaling and cell migration. Overall, IFNT is a primary regulator of endometrial gene expression, while PAG predominantly affected the transcriptome of circulating immune cells during early pregnancy. Further research is essential to fully grasp the roles of identified DEG in both the endometrium and blood leukocytes. Graphic abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=70 SRC="FIGDIR/small/591148v1_ufig1.gif" ALT="Figure 1"> View larger version (32K): org.highwire.dtl.DTLVardef@b51110org.highwire.dtl.DTLVardef@173433dorg.highwire.dtl.DTLVardef@4368e5org.highwire.dtl.DTLVardef@19bd118_HPS_FORMAT_FIGEXP M_FIG C_FIG Main findingsO_LIAcute IFNT signaling in the endometrium activates genes involved in inflammation while inhibiting vesicle transport in cells and ECM remodeling. C_LIO_LIProlonged IFNT signaling in the endometrium regulates genes involved in cell invasion and retinoic acid signaling. C_LIO_LIPAG alter gene expression in blood leukocytes more than in endometrium and may stimulate leukocyte differentiation while inhibiting leukocyte extravasation. C_LI

Study questionWhat are the temperature, pH and uterine fluid composition in the human uterus three days following a positive LH test or ovum pick-up? Summary answerThe mean uterine temperature was 36.94{+/-}0.26{degrees}C, the mean uterine pH was 6.76{+/-}0.22, and the concentrations of 37 components in aspirated uterine fluid were successfully determined. What is known alreadyEmbryo culture conditions in the laboratory impact key outcomes of IVF/ICSI treatments, such as the quality of the embryos and the live birth rate after treatment, and child outcomes, such as birth weight. Currently used conditions, including temperature, pH, and culture medium composition, are largely derived from clinical experience and experimental studies using animal models. Limited studies have been performed to determine the natural human preimplantation embryo environment in vivo during the physiologically relevant time of the menstrual cycle. This type of fundamental knowledge is required for evidence-based optimization of the in vitro embryo culture environment and improving IVF/ICSI outcomes. Study design, size, durationIn this cross-sectional study, conducted between April 2015 and March 2016, temperature and pH were measured in the human uterine cavity on the third day following a positive LH test or ovum pick-up, and uterine fluid was simultaneously aspirated for composition analysis. Uterine temperature was measured in fifty eight women, uterine pH was determined in fifty three women, and twenty two samples of aspirated uterine fluid were analysed for the concentrations of thirty-seven components. Participants/materials, setting, methodsThis study involved 61 healthy reproductive-aged women: 53 without ovarian stimulation and 8 who underwent ovarian stimulation. We measured uterine temperature using a probe inserted into the uterine cavity directly, and uterine pH after inserting a probe through the outer sheath of an IVF catheter. Uterine fluid was then aspirated using this outer IVF catheter and a 10 ml syringe, and subsequently analysed with a Cobas 8000 chemistry analyser and ultra-performance liquid chromatography-tandem mass spectrometry. Main results and the role of chanceThe mean uterine temperature on the third day following a positive LH test or ovum pick-up was 36.94 {+/-} 0.26{degrees}C and correlated with the womens core body temperature. The mean pH in the uterine cavity was pH 6.76 {+/-} 0.22, clearly lower than the standard pH used for human preimplantation embryo culture in vitro (pH 7.3 {+/-} 0.1). Concentrations of important energy sources were 0.8 {+/-} 0.02 mM pyruvate, 5.1 {+/-} 1.78 mM glucose and 6.60 {+/-} 1.12 mM lactate. Glutamic acid (1162 {+/-} 183 M), glycine (955 {+/-} 156 M) and alanine (513 {+/-} 82 M) were the most abundant amino acids in uterine fluid. Limitations, reasons for cautionIn absence of a preimplantation embryo, synergistic influences on the uterine environment may be overlooked. Single centre and specific population limitations may hinder broader generalization of the results. Uterine fluid likely contains additional components. Wider implications of the findingsThe in vivo uterine characteristics identified in this study are foundational to develop an in vivo evidence-based culture medium for human embryos. Further research is necessary to evaluate whether such a medium can improve human preimplantation embryo development and quality, thereby increasing cumulative live birth rates and improving child outcomes.

Human primordial germ cell-like cells (hPGCLCs) can be specified from human induced pluripotent stem cells (hiPSCs), offering a valuable model for human germ cell development. However, further maturation steps of hPGCLCs rely on mouse feeders, or co-culture with mouse gonadal somatic cells. Exposure of hPGCLCs to human embryonic niche has not been attempted. Here, we co-cultured female hPGCLCs in two distinct somatic compartments. In reconstituted ovary (rOv) culture, human fetal germ cells proliferate and initiate meiosis, while hPGCLCs upregulate gonadal germ cell markers such as DDX4. Additionally, hPGCLCs can be supported in 3D culture by the amnion-like cells (AMLC) generated during PGCLC differentiation. Compared to rOV, hPGCLCs are less prone to dedifferentiation in PGCLC/AMLC aggregates. Finally, we demonstrated that SCF is crucial for the survival of hPGCLCs but not second trimester fetal germ cells. Together, this work highlights a shift in niche is required in human germ cell development. In BriefChang and colleagues utilized in vitro reconstituted human fetal ovary (rOv) as somatic niche to mature human primordial germ cell-like cells (PGCLCs). hPGCLCs in rOv upregulate gonadal germ cell markers but are prone to dedifferentiation. In contrast, hPGCLCs cultured with amnion-like cells can be maintained without dedifferentiation. In both culture systems, SCF is crucial for the survival of hPGCLCs. HighlightsO_LIReconstituted human fetal ovaries (rOvs) support meiosis entry of fetal germ cells C_LIO_LIThe rOVs support hPGCLCs to upregulate gonadal germ cell markers C_LIO_LIhPGCLCs show less dedifferentiation in amnion-like cell aggregates compare to rOv C_LIO_LISCF is not required for survival of fetal germ cells, but crucial for hPGCLCs C_LI

ObjectiveTo facilitate in vitro mechanistic studies in pelvic inflammatory disease (PID) and subsequent tubal factor infertility, as well as ovarian carcinogenesis, we sought to establish patient tissue derived fallopian tube (FT) organoids and to study their inflammatory response to acute vaginal bacterial infection. DesignExperimental study. SettingAcademic medical and research center. PatientsFT tissues were obtained from four patients after salpingectomy for benign gynecological diseases. InterventionsWe introduced acute infection in the FT organoid culture system by inoculating the organoid culture media with two common vaginal bacterial species, Lactobacillus crispatus and Fannyhessea vaginae. Main Outcome MeasuresThe inflammatory response elicited in the organoids after acute bacterial infection was analyzed by the expression profile of 249 inflammatory genes. ResultsCompared to the negative controls that were not cultured with any bacteria, the organoids cultured with either bacterial species showed multiple differentially expressed inflammatory genes. Marked differences were noted between the Lactobacillus crispatus infected organoids and those infected by Fannyhessea vaginae. Genes from the C-X-C motif chemokine ligand (CXCL) family were highly upregulated in F. vaginae infected organoids. Flow cytometry showed that immune cells quickly disappeared during the organoid culture, indicating the inflammatory response observed with bacterial culture was generated by the epithelial cells in the organoids. ConclusionPatient tissue derived FT organoids respond to acute bacterial infection with upregulation of inflammatory genes specific to different vaginal bacterial species. FT organoids is a useful model system to study the host-pathogen interaction during bacterial infection which may facilitate mechanistic investigations in PID and its contribution to tubal factor infertility and ovarian carcinogensis.

Structured AbstractO_ST_ABSPurposeC_ST_ABSTo determine if rescue in vitro maturation (IVM) of human oocytes can be improved by co-culture with ovarian support cells (OSCs) derived from human induced pluripotent stem cells (hiPSCs). MethodsFertility patients undergoing conventional ovarian stimulation for oocyte cryopreservation or IVF donated denuded immature germinal vesicle (GV) and metaphase I (MI) oocytes for research, which were allocated between either the control or intervention cultures. Fertility patients aged 25 to 45 years old donated immature oocytes under informed consent, with no additional inclusion criteria. The 24-28 hour OSC-IVM culture condition was composed of 100,000 OSCs in suspension culture with human chorionic gonadotropin (hCG), recombinant follicle stimulating hormone (rFSH), androstenedione and doxycycline supplementation. The Media-IVM control lacked OSCs and contained the same supplementation. Primary endpoints consisted of MII formation rate and morphological quality assessment. Additionally, metaphase spindle assembly location and oocyte transcriptomic profiles were assessed compared to in vivo matured MII oocyte controls. ResultsWe observed significant improvement in maturation outcome rates ([~]1.7X) for oocytes that underwent IVM with OSCs. Specifically, the OSC-IVM group yielded a maturation rate of 62% {+/-} 5.57% SEM versus 37% {+/-} 8.96% SEM in the Media-IVM (p=0.0138, unpaired t-test). Oocyte morphological quality between OSC-IVM and the Media-IVM control did not significantly differ. OSC-IVM resulted in MII oocytes with no instances of spindle absence and no significant difference in position compared to in vivo matured IVF-MII controls. OSC-IVM treated MII oocytes display a transcriptomic signature significantly more similar to IVF-MII controls than the Media-IVM control MII oocytes did. ConclusionThe novel OSC-IVM platform is an effective tool for rescue maturation of human oocytes obtained from conventional stimulation cycles, yielding oocytes with improved nuclear and cytoplasmic maturation. OSC-IVM shows broad utility for application in modern fertility treatment to improve the total number of available mature oocytes for fertility treatment.

Ovarian stimulation (OS), utilized for the development of multiple ovarian follicles for IVF, induces supraphysiologic levels of E2 and an early rise in P4 that disrupt endometrial differentiation and decreases implantation rates or result in placental insufficiency and pregnancy complications. To improve pregnancy rates and reduce the risk of pregnancy complications associated with IVF, it is crucial to advance our molecular understanding of the molecular regulation of endometrial differentiation. Previous studies from our laboratory suggest G protein-coupled receptors (GPCRs) are important regulators of endometrial differentiation. To investigate this further, using a retrospective dataset, we identified all GPCRs expressed across the proliferative and secretory phase of the menstrual cycle and found that many members of the adhesion G protein-coupled receptor (ADGR) family are dynamically expressed. For each ADGR subfamily exhibiting differentially-expressed genes across the cycle, their expression was investigated by RT-PCR in the non-pregnant mouse uterus and decidua on E7.5 of pregnancy. For those genes expressed in the E7.5 decidua, their expression was further quantified by qPCR across early mouse pregnancy. The RT-PCR screen revealed expression of 13 ADGRs (4 of the 9 subfamilies) in E7.5 decidua and among these genes, many were differentially expressed between E0.5 and E5.5 or 6.5 and between E5.5 and E6.5. The dynamic expression of the ADGRs across the menstrual cycle and in early mouse pregnancy, suggests these ADGRs are E2- and/or P4-regulated genes. We therefore hypothesized that for these ADGR genes, mRNA expression would be disrupted in an OS cycle. This hypothesis was tested on endometrial biopsies collected in the secretory phase from prospective cohorts of women in natural and OS cycles. Consistent with the retrospective dataset, our data revealed that members of the ADGR gene family are expressed in the secretory phase of the natural menstrual cycle and for the first time, we show that their expression is altered by ovarian stimulation.

The oviduct comprises 4 main regions: infundibulum (oocyte pick-up), ampulla (fertilization), isthmus (sperm capacitation and reservoir, preimplantation embryonic development), and uterotubal junction (UTJ; sperm and embryo transport). Mounting evidence in livestock and rodents suggest that gametes alter gene expression in secretory and ciliated epithelial cells of the oviduct. To elucidate whether adaptive interactions between the oviduct and gamete/embryo exist, we performed bulk RNA-sequencing on oviductal tissues collected from infundibulum+ampulla (IA) or isthmus+UTJ (IU) at various developmental stages (0.5, 1.5, 2.5-, and 3.5-days post coitus (dpc)) in mice. Samples were also collected during days 0.5, 1.5, 2.5, and 3.5 of pseudopregnancy (dpp). We found a strong region (IA vs. IU)-specific expression of large clusters of genes. The transition from 0.5 dpc to other pregnancy timepoints induces large sets of differentially expressed genes (DEGs) in pregnancy and pseudopregnancy in both IA and IU regions. Specifically, genes involved in pro-inflammatory responses were detected in both IU and IA regions. The presence of sperm at 0.5 dpc induces DEGs involved in pro-inflammatory responses in the IU region with an enrichment of biological processes for inflammatory cytokines, macrophage, and neutrophil recruitment. Additionally, DEGs are enriched in mitogen-activated protein kinase (MAPK) pathways along with genes in the Dusp family, Map3k8, Il1b, and Il1r2, among others. However, at 1.5 dpc we observed a strong shift to an anti-inflammatory condition in the IU region. These observations were absent in 0.5 and 1.5 dpp, suggesting that the DEGs observed for those inflammatory responses during pregnancy were likely induced by the presence of sperm. scRNA-seq analysis revealed that the inflammatory responsive genes were likely produced by secretory epithelial cells, compared to other cell types in the oviduct. In addition, multiple DEGs involved in pyruvate and glycolysis were enriched in the IU region, which could provide metabolic support for developing embryos. Lastly, we have also identified that there were cells that express immune markers in the oviduct, indicating that the oviduct is an immuno-dynamic tissue. In conclusion, our findings indicate that the oviduct is adaptive and responsive to the presence of sperm and embryos in a spatiotemporal manner. In this report, we intend to disseminate our findings on the transcriptional profiles during different stages of pregnancy. The complete study and validation at the protein level are currently underway and will be updated as soon as the data are available.

In mammalian females, primordial follicles form during fetal ovarian development and serve as the only source to sustain adult ovarian function. Mechanisms underlying how primordial follicles assemble, maintain dormancy, activate for follicular development, and undergo cell death are important for understanding ovarian physiology and pathological conditions. Here, we demonstrate a protocol of culturing postnatal mouse ovaries on membrane inserts - an approach allowing culture, pharmaceutical treatment, and live-imaging of intact ovaries for up to 10 days depending on the developmental stage of the ovary. The change of culture conditions can be done by transferring inserts containing cultured ovaries between wells on a plate, avoiding physical interference with tissues during culture. In this experiment, we use postnatal day 5 (P5) CD1 mouse ovary culture as an example. P5 ovaries were isolated and placed on a 12 mm insert in a 24-well plate. Each ovary was separated within a droplet of DMEM/F12 medium supplemented with 10% FBS, 3 mg/ml BSA, 10 mIU/ml FSH, and Gibco Antibiotic-Antimycotic, and gently stabilized to the membrane insert. The medium was changed every two days, and the culture was maintained for five days. Following the culture, ovaries were fixed in 4% paraformaldehyde for two hours and processed for whole-mount antibody staining. Primordial follicles were visualized using confocal microscopy with anti-DDX4 antibody, allowing for the analysis of oocyte number and morphology. We showed that the number of primordial follicles in each ovary was significantly affected by whether tissues were properly placed on the membrane insert. Difference in the number of ovaries on each insert may contribute to non-biological variations and should be avoided.

Proper action of the female sex steroids, 17{beta}-estradiol (E2) and progesterone (P4) on endometrium is essential for fertility. Beyond its role in regulating the cell cycle, cyclin A2 (CCNA2) also mediates E2 and P4 signaling in vitro, but a potential role in modulating steroid action for proper endometrial tissue development and function is unknown. To fill this gap in our knowledge, we examined human endometrial tissue from fertile and infertile women for CCNA2 expression and correlated this with pregnancy outcome. Functional assessment of CCNA2 was validated in vivo using a conditional Ccna2 uterine deficient mouse model while in vitro function was assessed using human cell culture models. We found that CCNA2 expression was significantly reduced in endometrial tissue, specifically the stromal cells, from women undergoing in vitro fertilization who failed to achieve pregnancy. Conditional deletion of Ccna2 from moue uterine tissue recapitulated the inability to achieve successful pregnancy which appears to be due to alterations in the process of decidualization, which was confirmed using in vitro models. From these studies, we conclude that CCNA2 expression during the proliferative/regenerative stage of the menstrual cycle acts as a safeguard allowing for proper steroid responsiveness, decidualization and pregnancy. When CCNA2 expression levels are insufficient there is impaired endometrial responsiveness, aberrant decidualization and loss of pregnancy. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=100 SRC="FIGDIR/small/545284v1_ufig1.gif" ALT="Figure 1"> View larger version (18K): org.highwire.dtl.DTLVardef@150b471org.highwire.dtl.DTLVardef@176a804org.highwire.dtl.DTLVardef@110a47dorg.highwire.dtl.DTLVardef@19f186c_HPS_FORMAT_FIGEXP M_FIG C_FIG

Understanding the molecular pathways that underpin ovarian development and function is vital for improving the research approaches to investigating fertility. Despite a significant improvement in our knowledge of molecular activity in the ovary, many questions remain unanswered in the quest to understand factors influencing fertility and ovarian pathologies such as cancer. Here we present an investigation into the expression and function of developmental transcription factor LIM Homeobox 9 (LHX9) in the adult mouse ovary. We have characterised Lhx9 expression in several cell types of the mature ovary across follicle stages. To elucidate the function of this expression, we carried out an investigation of ovarian anatomy and transcription in a Lhx9+/- knockout mouse model displaying subfertility. Despite a lack of gross anatomical differences between genotypes, RNA-sequencing found that 90 genes were differentially expressed between Lhx9+/- and Lhx9+/+ mice. Gene ontology analyses revealed a downregulation of genes with major roles in ovarian steroidogenesis and an upregulation of genes with implications for ovarian cancer. Analysis of the ovarian epithelium revealed Lhx9+/- mice have a disorganised epithelial phenotype and a significant increase in epithelial marker gene expression. These results provide an analysis of Lhx9 in the adult mouse ovary and a new candidate for fertility research and ovarian epithelial cancer. Summary sentenceLhx9 haploinsufficient mice are subfertile with altered expression of steroid genes in the adult ovary and abnormal ovarian surface epithelium.

Study questionTo study the development of human embryos in a culture medium with pH 6.8 and composition based on previous in vivo human uterine measurements. Summary answerThe blastocyst formation rate of donated surplus human preimplantation embryos in embryo culture medium with pH 6.8 and uterine composition was similar to control medium. What is known alreadyIn vitro culture conditions can affect human preimplantation embryo development and fertility treatment success rates. The current IVF culture conditions are derived from using animal models, laboratory experience and limited human in vivo evidence. Therefore, we previously measured human in vivo uterine conditions on the third day following a positive LH test or ovum pick-up. Strikingly, the uterine pH at this time of the menstrual cycle (pH 6.8) appeared lower than the pH used for human preimplantation embryo culture in IVF laboratories worldwide (pH 7.2-7.4). Mimicking in vivo conditions may potentially improve in vitro embryo development, implantation rates, and overall fertility treatment and safety outcomes. Study design, size, durationIn this preclinical pilot study, 404 donated surplus human day 3 and day 4 embryos were cultured in one of four culture media: ULPC medium (uterine low pH and uterine fluid composition), UC medium (standard pH and uterine fluid composition), ULP medium (uterine pH and standard composition), or control medium (G-2 PLUS medium with standard pH and composition). Blastocyst formation rate on day 5 (after one or two days in culture) was the primary outcome to assess embryo development. Participants/materials, setting, methodsEmbryos were randomly allocated to the different culture conditions, stratified by sibling status and maternal age, before thawing. Day 3 and day 4 embryos were separately randomized, ensuring that each culture group contained an equal amount of both day 3 and day 4 embryos. All procedures and culture conditions were similar between groups, except for pH and medium composition. Embryo morphology was assessed immediately after thawing and on developmental day 5 for the primary outcome. Assessors were blinded to medium allocation. Main results and the role of chanceAll four culture media supported human preimplantation embryo development into blastocysts. Blastocyst formation rates on day five were 54/102 (52.9%) in ULPC medium, 44/104 (42.3%) in UC medium, 48/98 (49.0%) in ULP medium and 47/102 (46.1%) in control medium. Limitations, reasons for cautionThis study is limited by the use of donated surplus human day three and day four embryos. The effect of these new in vitro conditions on embryo development during the first three days of human embryo culture is not yet known. Wider implications of the findingsThe outcomes of this study indicate the need for further research on mimicking the in vivo uterine conditions for in vitro embryo culture using the conditions proposed here, including a lower pH (of 6.8) than currently used in IVF laboratories (pH 7.2-7.4).

Organoid technology has provided us with a unique opportunity to study early human development and decipher various steps involved in the pathogenesis of human diseases. The technology is already used in clinics to improve human patient outcomes. However, limited knowledge of the methodologies required to establish organoid culture systems in domestic animals has slowed the advancement and application of organoid technology in veterinary medicine. Here, we have developed a platform to grow organoids from animal tissue samples and characterized oviductal organoids from five domestic animal species. Organoids were grown progressively from single cells derived from the enzymatic digestion of freshly collected equine, bovine, feline, canine, and porcine oviducts. The addition of WNT, TGFB, BMP, Rock, and Notch signalling pathway activators or inhibitors in the culture medium suggested remarkable conservation of the molecular signals involved in oviductal epithelial development and differentiation across species. The gross morphology of organoids from all the domestic species was initially similar. However, some differences in size, complexity, and growth rate were observed and described. Well-defined and synchronised motile ciliated cells were observed in differentiated organoids in mature populations. Histopathologically, oviductal organoids mimicked their respective native tissue. In summary, we have developed a detailed cross-species comparison of oviductal organoid models, which will be valuable for advancing assisted reproductive technologies and fertility studies in these animal species in the future. Summary sentenceOrganoids can be derived from the oviductal epithelium of cow, cat, dog, horse, and pig to advance assisted reproductive technologies in animals.

During pregnancy uterine stromal cells undergo a mesenchymal to epithelial cell transition termed decidualization. In humans initiation of decidualization occurs in the absence of an embryo resulting in a need to identify embryo-independent molecular cues that can initiate decidualization. Although, similar to humans, decidualization in the mouse can be induced in the absence of an embryo, whether an implantation event is prerequisite for such decidualization is not known. In this study using different models of estrogen-dependent implantation, including natural (embryo) and artificial (sesame oil, agarose only beads, and Concanavalin A coated agarose beads) we determined that implantation chamber formation precedes decidualization. We show that focal stimuli, including the embryo, Concanavalin A coated bead, and oil droplets, induce V-shaped implantation chambers that lead to sub-epithelial PTGS2 expression and decidualization. Unfertilized eggs and uncoated agarose blue beads fail to form an implantation chamber and do not initiate decidualization. Further, we show that lectins that share sugar binding properties with Concanavalin A can also induce a V-shaped implantation chamber. Finally, using second harmonic generation we show that during decidualization collagen fibers spread radially away from the implantation chamber irrespective of the focal signal used for inducing the chamber. Thus, in the mouse artificial decidualization also initiates at the site of implantation chamber formation. These findings are critical when separating physical stimulus-dependent, embryo-dependent and embryo-independent mechanisms of decidualization that underlie a successful pregnancy.