Environmental exposures to organophosphorus flame retardants in early pregnancy and risks of gestational diabetes mellitus: a nested case-control study.

OPFRs are emerging environmental pollutants with reproductive and endocrine toxicity. This study aimed to examine the association between environmental exposure to OPFRs during early pregnancy and GDM. This nested case-control study was based on a birth cohort that was constructed at a maternal and child health hospital, including 74 cases of GDM among 512 pregnant women. The OPFRs, including TBP, TBEP, TCEP, TDCPP, TMCP, TOCP, and TPHP during 10-14 weeks of pregnancy were determined using GC-MS. The association between the OPFRs and GDM was assessed using WQS and BKMR models. The levels of OPFRs were significantly elevated in GDM patients (60) compared with the controls (90). The WQS analysis showed that mixtures of the OPFRs were significantly associated with GDM (OR 1.370, 95% CI 1.036-1.810, P = 0.027), and TBP, TPHP, and TMCP were the major contributors to the mixed exposure effect. In the BKMR model, individual exposure to TBP, TPHP, and TMCP, and the interaction of TMCP with TBP and TPHP were significantly associated with GDM. Environmental exposure to OPFRs is positively associated with GDM. These findings provide evidence for the adverse effects of OPFR exposure on the health of pregnant women.

Assessment of toxic metal pollution in Yueqing Bay and the extent of metal-induced oxidative stress in Tegillarca granosa raised in this water.

Yueqing Bay is an important economic shellfish culture zone in Zhejiang Province, China. However, increased pollution in the water caused by toxic metals has led to the bioaccumulation of toxic metals in cockles such as Tegillarca granosa, and the consequence of toxic metal-associated toxicity in these animals. This study aimed to assess the concentration of toxic metals in the water and sediment in four different sites (Baisha, Qingjiang, Nanyue, and Wengyang) within Yueqing Bay and to evaluate the extent of metal bioaccumulation in T. granosa raised in the aquaculture farms located within the four sites, as well as the changes in biomarkers in T. granosa in response to the metals. The assessment was carried out at two different times of the year, January and July. The water and sediment samples taken from the aquaculture farms in Baisha (S1), Qingjiang (S2) and Nanyue (S3) were found to have a comprehensive toxic metal pollution index (Pc) <1, indicating that these farms were not polluted. However, the water and sediment samples taken from the aquaculture farm in Wengyang (S4) had a Pc between 1 and 2, indicating mild toxic metal pollution. The edible risk assessments (HQ) of T. granosa in all four farms were <1, and therefore, these cockles could be considered safe for human consumption. The toxic metal enrichment in T. granosa exhibited a strong correlation with the toxic metal content in the sediment. In all four farms, CAT and SOD activity levels in the visceral mass of T. granosa were higher than those found in the foot, and a significantly higher level of CAT activity was detected in July compared with January. Similarly, MDA and H2O2 contents in the visceral mass were also higher in July than in January. Tegillarca granosa individuals taken from S4 and S3 farms exhibited significantly higher levels of metallothionein (MT) mRNA and MDA compared with individuals from S1 and S2 farms. Furthermore, the levels of MDA and MT mRNA showed significant positive correlations with Cd, Cr, Hg, and Cu. Elevation of lipid peroxidation in these cockles coincided with increasing levels of endogenous antioxidants. The visceral mass of T. granosa and its MDA level could be used as a tissue indicator and a biochemical marker, respectively, for detecting toxic metal pollution. MT mRNA might also be used as a molecular marker of toxic metal pollution. The integrated biomarker response version 2 (IBRv2) values of the four aquaculture farms in Yueqing Bay showed the order S4 > S3 > S2 > S1, indicating that S4 had the most serious metal-induced stress. Furthermore, the IBRv2 values correlated with the Nemerow composite index (Pc) for all the cockles examined. Thus, as far as the contamination of aquaculture farms in Yueqing Bay by toxic metals is concerned, the aquaculture farm in Wengyang (S4) was mildly contaminated by toxic metals. However, the contamination was relatively low, presenting a low risk for the local population of T. granosa.

Association between serum LH levels on hCG trigger day and live birth rate after fresh embryo transfer with GnRH antagonist regimen in different populations.

Objective: To investigate whether serum LH levels on hCG trigger day are associated with live birth rate (LBR) after fresh embryo transfer with GnRH antagonist regimen in different populations. Methods: This study was a retrospective study. A total of 3059 fresh embryo transfers were divided into three populations: predicted normal ovarian responders (NOR) (n=2049), patients with PCOS (n=533), and predicted poor ovarian responders (POR) (n=477). Each population was stratified into three groups based on LH levels: < 25th percentile, 25-75th percentile, and > 75th percentile. The primary outcome of the study was LBR, and secondary outcomes included implantation, clinical pregnancy, and early pregnancy loss rates. Univariable and multivariable regression analyses were performed to adjust for potential confounders. Results: In NOR, compared to the reference group (>75th percentile), LBR was significantly lower in the < 25th percentile group (adjusted OR=0.662; 95%CI, 0.508-0.863) and 25-75th percentile group (adjusted OR=0.791; 95%CI, 0.633-0.988). In PCOS patients, LBR decreased significantly in the < 25th percentile group (41.4%) compared to the 25-75th percentile group (53.7%) and > 75th percentile group (56.1%). In addition, the LBR was lower in the < 25th percentile group (33.6%) compared with the 25-75th percentile group (43.4%) and the>75th percentile group (42.0%) in POR, but this was not statistically significant. Conclusions: High serum LH levels are associated with increased LBR after fresh embryo transfer in GnRH antagonist cycles, which may be attributable to higher implantation rate. LH may be a predictor of whether to schedule fresh embryo transfer in IVF cycles for better clinical outcomes.

Attenuated effect of zinc gluconate on oxidative stress, inflammation, and angiogenic imbalance in pre-eclampsia rats.

AIMS: Pre-eclampsia (PE) is a common obstetric disease associated with oxidative stress, systemic inflammation, and angiogenic imbalance, whereas zinc (Zn) presents anti-oxidative and anti-inflammatory effects. This study is to investigate whether zinc gluconate (ZG) supplementation may ameliorate the early signs, adverse pregnancy outcomes, and pathogenic processes of PE in an animal model. MAIN METHODS: Forty pregnant Wistar rats were randomly divided into four groups: blank control (treated with normal saline, NS), Zn control (treated with ZG and followed by NS), PE model (treated with NS and followed by nitro-L-arginine methyl ester, L-NAME), and PE intervention (treated with ZG and followed by L-NAME). ZG (5 mg/kg/day) or NS was administered by gavage from day 0 to 19 of gestation, and L-NAME (80 mg/kg/day) or NS was subcutaneously injected from day 4 to 19 of gestation. The blood pressure, urinary protein, and pregnancy outcomes were recorded. Oxidative stress, inflammation, and angiogenic homeostasis were evaluated. KEY FINDINGS: PE rats exhibited oxidative stress (reduced SOD, CAT, and GSH, and increased MDA and 3-NT), inflammation (increased IL-6 and TNF-α), and angiogenic imbalance (reduced VEGF and PlGF, and increased sFlt-1). After intervention with ZG, the blood pressure and urinary protein levels were reverted, and the pregnancy outcomes were improved. The oxidative stress, inflammation, and angiogenic imbalance were effectively restored in accompany by increased Zn and MT levels. SIGNIFICANCE: ZG can ameliorate the early signs and pathological processes of PE in the animal model, indicating the value of zinc supplementation during pregnancy for PE prevention.

Role of diffusion-weighted imaging in differentiating angiomatous meningioma from atypical meningioma.

BACKGROUND: Conventional magnetic resonance imaging (MRI) characteristics of angiomatous meningioma (AM) and atypical meningioma (ATM) sometimes overlap. However, there are significant differences in the treatment and prognosis of the two tumors. The aim of the study was to assess the role of diffusion-weighted imaging (DWI) in differentiating AM from ATM. METHODS: Clinical, MRI, and pathological data of 25 patients with AM and 30 patients with ATM were retrospectively analyzed. Main clinical indexes, conventional MRI characteristics, and apparent diffusion coefficient (ADC) values were compared between the two groups, and receiver operating characteristic (ROC) curves were drawn to determine the diagnostic performance of ADC values in distinguishing AM from ATM. RESULTS: The minimum ADC value (ADCmin), average ADC value (ADCmean), and relative ADC value (rADC) for AM (908.00 ± 117.00 × 10-6 mm2/s, 921.04 ± 67.09 × 10-6 mm2/s, and 1.15 ± 0.09, respectively) were significantly higher than those for ATM (710.50 ± 79.80 × 10-6 mm2/s, 748.50 ± 67.27 × 10-6 mm2/s, and 0.96 ± 0.09, respectively; all P < 0.05). ROC analysis showed that ADCmin had the best diagnostic performance in distinguishing AM from ATM, with an area under the curve value of 0.977. When using 759.00 × 10-6 mm2/s as the optimal threshold, the sensitivity, specificity, accuracy, positive predictive value, and negative predictive value were 90.00 %, 96.00 %, 92.72 %, 96.40 %, and 88.90 %, respectively. CONCLUSIONS: DWI plays an important role in differentiating AM from ATM, and ADCmin is the most promising potential parameter that can improve the preoperative diagnostic accuracy of both tumors.

Value of energy spectrum CT parameters in the differential diagnosis of high-grade clear cell renal cell carcinoma and type II papillary renal cell carcinoma.

BACKGROUND: Energy spectrum computed tomography (CT) has become a promising approach for the differential diagnosis of tumor subtypes. PURPOSE: To explore the value of energy spectrum CT parameters in the differential diagnosis of high-grade clear cell renal cell carcinoma (ccRCC) and type II papillary renal cell carcinoma (pRCC). MATERIAL AND METHODS: Forty-two cases of high-grade ccRCC and 28 cases of type II pRCC were retrospectively reviewed. All region of interest (ROI) measurements were maintained consistently between the two-phase contrast-enhanced examinations. The ROIs encompassed as much of the enhancing areas of the lesions as possible. Energy spectrum CT parameters of all cases, including the 70 keV (HU) value, normalized iodine concentration (NIC), and energy spectrum curve slope were recorded by two radiologists with over 10 years of experience in abdominal CT diagnosis. RESULTS: In the cortical phase (CP) and parenchymal phase (PP), the 70 keV (HU) value, NIC, and slope value of the energy spectrum curve of high-grade ccRCC were significantly higher than those of type II pRCC. In the CP, NIC showed the highest differential diagnosis efficiency for the two group tumors, with a sensitivity of 78.9% and a specificity of 77.0%. There was no statistical difference in tumor hemorrhage, tumor envelope, tumor morphology, tumor border, lymph node metastasis, embolism, renal pelvis invasion, or tumor calcification between the two tumor types. However, there was significant difference in the number of tumors (P = 0.019). CONCLUSION: Energy spectrum CT parameters are valuable for the differential diagnosis of high-grade ccRCC and type II pRCC.

Gestational Folic Acid Administration Alleviated Maternal Postpartum Emotional and Cognitive Dysfunction in Mice.

Gestational folic acid (FA) supplementation has been widely recognized for its benefits in preventing offspring defects, but its effect on postpartum females has not yet been adequately assessed. The occurrence of emotional and cognitive dysfunction is common in postpartum women, and its treatment remains limited. Considering the promising results of FA in various psychiatric disorders both in human and redents, we tested the effect of gestational FA administration on postpartum psychiatric behavioral phenotypes and the implicated brain-related mechanisms in a murine model. FA was administered orally in both the hormone-stimulated-pregnancy (HSP) model and pregnant mice at doses of 1 and 5 mg/kg. Postpartum behavioral results showed that the disorders of cognitive performance, depressive, and anxiety-related behaviors were all alleviated in the 5 mg/kg FA group. However, the general development of their offspring remained unaffected. Immunofluorescence and immunoblot results revealed that FA pretreatment significantly activated the maternal hippocampal BDNF-related pathway. Morphological studies have confirmed that FA promotes hippocampal neurogenesis. Moreover, synaptic plasticity and synaptic transmission are enhanced. All of these hippocampal changes play critical roles in rescuing neuronal function and behaviors. Thus, our data suggest that gestational FA administration has a therapeutic effect that improves cognition and reduces depression and anxiety in a murine postpartum model. This may be developed as a preventive and adjuvant therapeutic option for pregnant women.

Differential diagnosis of chromophobe renal cell carcinoma and papillary renal cell carcinoma with dual-energy spectral computed tomography.

BACKGROUND: Computed tomography (CT) image features of chromophobe renal cell carcinoma (ChRCC) and papillary renal cell carcinoma (PRCC) are, occasionally, sometimes difficult to identify. However, spectral CT might provide quantitative parameters to differentiate them. PURPOSE: To differentiate between ChRCC and PRCC with quantitative parameters using spectral CT. MATERIAL AND METHODS: Forty cases of RCC confirmed with pathological tests were analyzed retrospectively (27 cases of PRCC and 13 cases of ChRCC). All patients underwent non-enhanced CT and dual-phase contrast-enhanced CT scans. For each lesion, the CT value of monochromatic images as well as iodine and water concentrations were measured, and the slope of spectrum curve was calculated. Data were analyzed using Student's t-test. Sensitivity and specificity of the quantitative parameters were analyzed using the receiver operating characteristic (ROC) curve. RESULTS: During the cortex phase (CP) and parenchyma phase (PP), the CT value and slope of spectrum curve of ChRCC were higher than those of PRCC, and significant differences were observed at low energy levels (40-70 keV). Normalized iodine concentration of ChRCC and that of PRCC was significantly different during CP and PP (P < 0.05). The water (iodine) concentrations of ChRCC and PRCC in CP and PP were not statistically different (P > 0.05). All the ROCs for parameters were above the reference line. CONCLUSION: Spectral CT may help increase the diagnostic accuracy of differentiating PRCC from ChRCC using a quantitative analysis.

Liq_ccRCC: Identification of Clear Cell Renal Cell Carcinoma Based on the Integration of Clinical Liquid Indices.

Currently, preoperative diagnosis and differentiation of renal clear cell carcinoma and other subtypes remain a serious challenge for doctors. The liquid biopsy technique and artificial intelligence have inspired the pursuit of distinguishing clear cell renal cell carcinoma using clinically available test data. In this work, a method called liq_ccRCC based on the integration of clinical blood and urine indices through machine learning approaches was successfully designed to achieve this goal. Clinically available biochemical blood data and urine indices were collected from 306 patients with renal cell carcinoma. Finally, the integration of 18 top-ranked clinical liquid indices (13 blood samples and 5 urine samples) was proven to be able to distinguish renal clear cell carcinoma from other subtypes of renal carcinoma by cross-valuation with an AUC of 0.9372. The successful introduction of this identification method suggests that subtype differentiation of renal cell carcinoma can be accomplished based on clinical liquid test data, which is noninvasive and easy to perform. It has huge potential to be developed as a promising innovation strategy for preoperative subtype differentiation of renal cell carcinoma with the advantages of convenience and real-time testing. liq_ccRCC is available online for the free test of readers at http://lishuyan.lzu.edu.cn/liq_ccRCC.

Optimization of an Aqueous Two-Phase System for the Determination of Trace Ethyl Carbamate in Red Wine.

In this study, a novel method using gas chromatography-mass spectrometry coupled with ethanol and K2HPO4 aqueous two-phase system (ATPS) was established for the quantitative determination of trace ethyl carbamate (EC) in red wine. The parameters that influence EC extraction in an aqueous two-phase system, including extraction temperature, time, pH, and ethanol concentration, were optimized. Method validation results indicated that the regression coefficient of the proposed method was 0.9979 in the linear range of 10 to 100 µg/L, and the limits of detection and quantification were 2.8 and 9.2 µg/L, respectively. Four red wine samples made from different grape varieties were processed by the proposed method for the repeatability verification, and EC concentrations were between 15.8 and 37.3 µg/L, with the relative standard deviations ranging from 3.5 to 6.6%. Results of the precision assay showed the average recovery of EC in red wine at 95.4 to 107.1%, with the relative standard deviations ranging from 1.4 to 6.2%. This method proved to be simple and reliable for quantitative determination of trace EC in red wine and would give guidance for quality monitoring of various red wines in the production process.

Gastrointestinal stromal tumor risk classification: spectral CT quantitative parameters.

PURPOSE: To examine the value of spectral CT quantitative parameters in gastrointestinal stromal tumor (GIST) risk classification. MATERIALS AND METHODS: This retrospective study was approved by the institutional review board. The requirement for informed consent was signed. The authors evaluated 86 patients (30 high risk, 22 medium risk, 28 low risk, and 6 very low risk; mean age: 59 years [range 19-83 years]) with pathologically confirmed GIST who underwent plain and triple-phase contrast-enhanced CT with spectral CT imaging mode from March 2015 through September 2017, with manual follow-up. Quantitative parameters including the CT value of 70 keV monochromatic images, the slope of spectral curves, and the normalized iodine concentration (NIC) and water (iodine) concentrations were measured and calculated, and conducted a power analysis of the above data. RESULTS: (1) The CT values at 70 keV of the high-risk group were higher than the intermediate and low groups in each of the enhanced phases (P ≤ 0.001), no significant differences in the intermediate-risk and low-risk groups were noted (P = 0.874, 0.871, 0.831, respectively). (2) The slope of the spectral curve of the high-risk group was higher than those of the intermediate and low groups in each of the enhanced phases (P ≤ 0.001), and there were no significant differences between the intermediate- and low-risk groups (P = 0.069, 0.466, 0.840, respectively). (3) The NIC of the high-risk group significantly differed from the lower risk groups (P ≤ 0.001). There was also no significant difference observed between the intermediate- and low-risk groups (P = 0.671, 0.457, 0.833, respectively). (4) The power analysis results show that only the low-risk group with delay period is 0.530, the rest groups are all greater than 0.999. CONCLUSION: Dual-energy spectral CT with quantitative analysis may help to increase the accuracy in differentiating the pathological risk classification of GIST between high risk and non-high risk, preoperatively. There were limitations for distinguishing the intermediate- and low-risk groups.

Excimer Disaggregation Enhanced Emission: A Fluorescence "Turn-On" Approach to Oxoanion Recognition.

A new approach to anion sensing that involves excimer disaggregation induced emission (EDIE) is reported. It involves the anion-mediated disaggregation of the excimer formed from a cationic macrocycle. This leads to an increase in the observed fluorescence intensity. The macrocycle in question, cyclo[1] N2, N6-dimethyl- N2, N6-bis(6-(1 H-imidazolium-1-yl)pyridin-2-yl)pyridine-2,6-diamine[1]1,4-dimethylbenzene (12+; prepared as its PF6- salt), is obtained in ca. 70% yield via a simple cyclization. X-ray diffraction analyses of single crystals revealed that, as prepared, this macrocycle exists in a supramolecular polymeric form in the solid state. Macrocycle 12+ is weakly fluorescent in acetonitrile. The emission intensity is concentration dependent, with the maximum intensity being observed at [12+] ≈ 0.020 mM. This finding is ascribed to formation of an excimer, followed possibly by higher order aggregates as the concentration of 12+ is increased. Addition of tetrabutylammonium pyrophosphate (HP2O73-) to 12+ (0.020 mM in acetonitrile) produces a ca. 200-fold enhancement in the emission intensity (λex = 334 nm; λem = 390-650 nm). These findings are rationalized in terms of the HP2O73- serving to break up essentially non-fluorescent excited-state dimers of 12+ through formation of a highly fluorescent anion-bound monomeric complex, 12+·HP2O73-. A turn-on in the fluorescence intensity is also seen for H2PO4- and, to a lesser extent, HCO3-. Little (HSO4-, NO3-) or essentially no (N3-, SCN-, F-, Cl-, Br- and I-) response is seen for other anions. Solid-state structural analysis of single crystals obtained after treating 12+ with HP2O73- in the presence of water revealed a salt form wherein a H2P2O72- anion sits above the cone-like macrocycle.

Analysis of dual energy spectral CT and pathological grading of clear cell renal cell carcinoma (ccRCC).

OBJECTIVE: To discuss the dual energy spectral computer tomography (CT) imaging features of the pathological grading of clear cell renal cell carcinoma (ccRCC) and the correlation between spectral CT imaging features and pathology. MATERIALS AND METHODS: We performed analyses of 62 patients with confirmed diagnosis of ccRCC. All patients underwent non-enhanced CT and dual-phase (cortex phase, CP and parenchyma phase, PP) contrast-enhanced CT with dual energy spectral mode. The subjects were pathologically divided into two groups: low-grade group (Fuhrman 1/2) and high-grade group (Fuhrman 3/4). The CT value of each lesion was measured on the monochromatic image at 70 keV. The normalized iodine concentrations (NIC) and the slope of the spectrum curve were calculated. The qualitative morphological parameters, including tumor shape, calcification, pseudocapsule, necrosis, and enhancement mode, were compared between the two groups. The quantitative data were compared using Student's t-test, and the enumeration data were analyzed using the chi-square test between low-grade and high-grade ccRCC.Receiver operating characteristic curve was used to determine the sensitivity and specificity of the quantitative parameters in two groups. RESULTS: The CT value, NIC, and mean slope of the low-grade group were increased compared with the high-grade group during CP (P = 0.001, P = 0.043, and P<0.001, respectively). The CT did not differ significantly during PP (P = 0.134); however, the NIC and mean slope varied considerably in the low grade compared with the high-grade group (P = 0.048, P = 0.017, respectively). The CT threshold value, NIC, and slope had high sensitivity and specificity in differentiating low-grade ccRCC from high-grade ccRCC. The tumor shape, pseudocapsule, and necrosis differed significantly between the two groups (P<0.05). CONCLUSIONS: Dual energy spectral CT with the quantitative analysis of iodine concentration and qualitative analysis of morphological characteristics increases the accuracy of diagnosing the pathological grade of ccRCC.

[Uterine macrophages affect embryo implantation via regulating vascular endothelial growth factor A in mice].

OBJECTIVE: To investigate the role of endometrial macrophages in embryo implantation and in regulating the expression of vascular endothelial growth factor A (VEGFA) in mouse endometrium during the peri-implantation period. METHOD: At D3.5 (D0.5 defined as the morning when a vaginal plug was observed), pregnant mice were divided randomly into experimental group, control group and blank group. In the experimental group, the mice were subjected to intrauterine injection of clodronate liposomes on the left side of uterus to eliminate the macrophages, and PBS liposomes on the right side. PBS liposomes and PBS were administered in the control and blank groups, respectively. The uterine tissues were collected on D5.5 and stained with trypan blue to show the implantation sites. Flow cytometry was performed to examine the percentage of F4/80(+) CD11b(+) macrophages macrophages in the uterus. F4/80(+) macrophage population within the endometrium and ovary and changes in VEGFA expression at the implantation and non-implantation sites were examined using immunohistochemistry. RESULTS: Endometrial F4/80(+) CD11b(+) macrophages macrophages were significantly reduced by 74% following intrauterine injection of clodronate liposomes (P<0.05). The number of macrophages in the ovaries showed no significant difference among the 3 groups. In the experimental group, the left side of the uterine showed imcomplete cavity closure with a lower number of implantation site than the right side (2.20∓1.81 vs 5.10∓1.91, P<0.05). VEGFA expression at the implantation site were significantly decreased in the endometrium on the left side with macrophage suppression as compared with that on the right side (P<0.05). CONCLUSION: Endometrial macrophages appear to modulate uterine receptivity by regulating the expression of VEGFA to affect embryo implantation, suggesting the important role of macrophages in embryo implantation.

[Media of rat macrophage NR8383 cells with prostaglandins E2-induced VEGF over-expression promotes migration and tube formation of human umbilical vein endothelial cells].

OBJECTIVE: To investigate the effect of prostaglandins E2 (PGE2) in enhancing vascular endothelial growth factor (VEGF) expression in a rat macrophage cell line and the effect of the media from PGE2-inuced rat macrophages on angiogenetic ability of human umbilical vein endothelial cells (HUVECs) in vitro. METHODS: Western blotting and qPCR were employed to investigate the expressions of VEGF protein and mRNAs in rat macrophage cell line NR8383 stimulated by PGE2 in the presence or absence of EP2 receptor inhibitor (AH6809) and EP4 receptor inhibitor (AH23848). Conditioned supernatants were obtained from different NR8383 subsets to stimulate HUVECs, and the tube formation ability and migration of the HUVECs were assessed with Transwell assay. RESULTS: PGE2 stimulation significantly enhanced the expression of VEGF protein and mRNAs in NR8383 cells in a dose-dependent manner. The supernatants from NR8383 cells stimulated by PGE2 significantly enhanced tube formation ability of HUVECs (P<0.05) and promoted the cell migration. Such effects of PGE2 were blocked by the application of AH6809 and AH23848. CONCLUSION: PGE2 can dose-dependently increase VEGF expression in NR8383 cells, and the supernatants derived from PGE2-stimulated NR8383 cells can induce HUVEC migration and accelerate the growth of tube like structures. PGE2 are essential to corpus luteum formation by stimulating macrophages to induce angiogenesis through EP2/EP4.