hCG-dependent regulation of angiogenic factors in human granulosa lutein cells

SMAD-dependent signaling mediates morphogenetic protein 6-induced stimulation of connective tissue growth factor in luteinized human granulosa cells†

Connective tissue growth factor (also known as CTGF or CCN2) is a secreted matricellular protein that belongs to the CCN family. With wide-ranging biological activities and tissue expression patterns, CTGF plays a critical role in regulating various cellular functions. In the female reproductive system, CTGF is highly expressed in granulosa cells in growing ovarian follicles and is involved in the regulation of follicular development, ovulation, and luteal function. In the mammalian ovary, bone morphogenetic protein 6 (BMP6) is an important intraovarian modulator of follicular development. In this study, we demonstrated that BMP6 treatment significantly increased the expression of CTGF in both primary and immortalized human granulosa cells. Using both pharmacological inhibitors and Small interfering RNA-mediated knockdown approaches, we showed that ALK2 and ALK3 type I receptors are required for BMP6-induced cellular activities. Furthermore, this effect is most likely mediated by a Sma- and Mad-related protein (SMAD)-dependent pathway. Our studies provide novel insight into the molecular mechanisms by which an intraovarian growth factor affects the production of another factor via a paracrine effect in human granulosa cells.

Sp1 regulates steroidogenic genes and LHCGR expression in primary human luteinized granulosa cells

Luteinizing hormone and human chorionic gonadotropin (hCG) bind to the luteinizing hormone/chorionic gonadotropin receptor (LHCGR). LHCGR is required to maintain corpus luteum function but the mechanisms involved in the regulation of LHCGR in human luteal cells remain incompletely understood. This study aimed to characterize the expression of LHCGR mRNA in primary human luteinized granulosa cells (hLGCs) obtained from patients undergoing in vitro fertilization and to correlate LHCGR expression with the response of hLGCs to hCG by assessing the expression of genes known to be markers of hCG actions. The results show that LHCGR expression is low in freshly isolated cells but recovers rapidly in culture and that hCG maintains LHCGR expression, suggesting a positive feedback loop. The activity of a LHCGR-LUC reporter increased in cells treated with hCG but not with follicle-stimulating hormone. Treatment with hCG also stimulated the expression of genes involved in steroidogenesis in a time-dependent manner. LHCGR promoter expression was found to be regulated by SP1, which we show is highly expressed in hLGCs. Moreover, SP1 inhibition prevented the stimulation of steroidogenic genes and the increase in LHCGR-LUC reporter activity by hCG. Finally, we provide evidence that a complex formed by SP1 and GATA4 may play a role in the maintenance of LHCGR expression. This report reveals the mechanisms involved in the regulation of the LHCGR and provides experimental data demonstrating that the proximal region of the LHCGR promoter is sufficient to drive the expression of this gene in primary hLGCs.

Involvement of human chorionic gonadotropin in regulating vasculogenic mimicry and hypoxia-inducible factor-1α expression in ovarian cancer cells

BACKGROUND

Human chorionic gonadotropin (hCG) can play a crucial role in angiogenesis. In the present study, we focused on hCG to gain insight into its potential effects on vasculogenic mimicry (VM) in ovarian cancer cells.

METHODS

Ovarian cancer OVCAR-3 cells were incubated with different concentrations of recombinant hCG in 3-dimensional cultures. VM was identified by morphological observations and vascular endothelial cell marker detection in OVCAR-3 cells. Expression of hCG, hypoxia-inducible factor-1α (HIF-1α), and the endothelial cell markers CD31, VEGF, and factor VIII were detected by reverse transcription polymerase chain reaction and western blotting. The effect of hCG on endothelial cell-marker expression in ovarian cancer cells was further explored using small interfering RNA (siRNA) and plasmid-based approaches.

RESULTS

Incubation of OVCAR-3 cells with recombinant hCG induced vessel-like network formation, which was accompanied by significant elevation of vascular marker expression. Attenuation of hCG expression by siRNA in OVCAR-3 cells suppressed the expression of endothelial cell markers and HIF-1α by tumour cells. Overexpression of hCG in OVCAR-3 cells resulted in increased expression of endothelial cell markers and HIF-1α.

CONCLUSIONS

HCG was crucial for changing the phenotype of OVCAR-3 cells to endothelial-like cells. The effect of hCG induction on VM in ovarian cancer cells is potentially associated with HIF-1α.

Luteinizing hormone/chorionic gonadotrophin receptor overexpressed in granulosa cells from polycystic ovary syndrome ovaries is functionally active

Polycystic ovarian syndrome (PCOS) is associated with anovulatory infertility. Luteinizing hormone/chorionic gonadotrophin receptor (LHCGR), which is critical for ovulation, has been suggested to be expressed prematurely in the ovarian follicles of women with PCOS. This study aimed to analyse the expression and activity of LHCGR in ovarian granulosa cells from PCOS patients and the involvement of ARF6 small GTPase in LHCGR internalization. Granulosa cells (GC) isolated from follicular fluid collected during oocyte retrieval from normal women (n = 19) and women with PCOS (n = 17) were used to study differences in LHCGR protein expression and activity between normal and PCOS patients. LHCGR expression is up-regulated in GC from PCOS women. LHCGR in PCOS GC is functionally active, as shown by increased cAMP production upon human gonadotrophin (HCG)-stimulation. Moreover, ARF6 is highly expressed in GC from PCOS patients and HCG-stimulation increases the concentrations of active ARF6. The inhibition of ARF6 activation attenuates HCG-induced LHCGR internalization in both normal and PCOS GC, indicating that there are no alterations in LHCGR internalisation in GC from PCOS. In conclusion, the expression and activation of LHCGR and ARF6 are up-regulated in GC from PCOS women but the mechanism of agonist-induced LHCGR internalization is unaltered.

Growth differentiation factor 8 suppresses cell proliferation by up-regulating CTGF expression in human granulosa cells

Connective tissue growth factor (CTGF) is a matricellular protein that plays a critical role in the development of ovarian follicles. Growth differentiation factor 8 (GDF8) is mainly, but not exclusively, expressed in the mammalian musculoskeletal system and is a potent negative regulator of skeletal muscle growth. The aim of this study was to investigate the effects of GDF8 and CTGF on the regulation of cell proliferation in human granulosa cells and to examine its underlying molecular determinants. Using dual inhibition approaches (inhibitors and small interfering RNAs), we have demonstrated that GDF8 induces the up-regulation of CTGF expression through the activin receptor-like kinase (ALK)4/5-mediated SMAD2/3-dependent signaling pathways. In addition, the increase in CTGF expression contributes to the GDF8-induced suppressive effect on granulosa cell proliferation. Our findings suggest that GDF8 and CTGF may play critical roles in the regulation of proliferative events in human granulosa cells.

An HCG-rich microenvironment contributes to ovarian cancer cell differentiation into endothelioid cells in a three-dimensional culture system

We investigated the expression of human chorionic gonadotropin (HCG) and its effects on vasculogenic mimicry (VM) formation in ovarian cancer cells under normoxic and hypoxic conditions in three-dimensional matrices preconditioned by an endothelial-trophoblast cell co-culture system. The co-culture model was established using human umbilical vein endothelial cells (HUVECs) and HTR-8 trophoblast cells in a three-dimensional culture system. The co-cultured cells were removed with NH4OH, and ovarian cancer cells were implanted into the preconditioned matrix. VM was identified morphologically and by detecting vascular markers expressed by cancer cells. The specificity of the effects of exogenous HCG in the microenvironment was assessed by inhibition with a neutralizing anti-HCG antibody. HCG siRNA was used to knock down endogenous HCG expression in OVCAR-3 ovarian cancer cells. HTR-8 cells 'fingerprinted' HUVECs to form capillary-like tube structures in co-cultures. In the preconditioned HCG-rich microenvironment, the number of vessel-like network structures formed by HCG receptor-positive OVCAR-3 cells and the expression levels of CD31, VEGF and factor VIII were significantly increased. The preconditioned HCG-rich microenvironment significantly increased the expression of hypoxia inducible factor-1α (HIF‑1α) and VM formation in OVCAR-3 cells under hypoxic conditions. Treatment with a neutralizing anti-HCG antibody but not HCG siRNA significantly inhibited the formation of vessel-like network structures. HCG in the microenvironment contributes to OVCAR-3 differentiation into endothelioid cells in three-dimensional matrices preconditioned with an endothelial-trophoblast cell co-culture system. HCG may synergistically enhance hypoxia-induced vascular markers and HIF-1α expression. These findings would provide perspectives on new therapeutic targets for ovarian cancer.

TGF-β1 Up-Regulates Connective Tissue Growth Factor Expression in Human Granulosa Cells through Smad and ERK1/2 Signaling Pathways

Connective tissue growth factor (CTGF), which is also called CCN2, is a secreted matricellular protein. CTGF regulates various important cellular functions by interacting with multiple molecules in the microenvironment. In the ovary, CTGF is mainly expressed in granulosa cells and involved in the regulation of follicular development, ovulation and luteinization. TGF-β1 has been shown to up-regulate CTGF expression in rat and hen granulosa cells. However, the underlying molecular mechanisms of this up-regulation remain undefined. More importantly, whether the stimulatory effect of TGF-β1 on CTGF expression can be observed in human granulosa cells remains unknown. In the present study, our results demonstrated that TGF-β1 treatment up-regulates CTGF expression in both immortalized human granulosa cells and primary human granulosa cells. Using a siRNA-mediated knockdown approach and a pharmacological inhibitor, we demonstrated that the inhibition of Smad2, Smad3 or ERK1/2 attenuates the TGF-β1-induced up-regulation of CTGF. This study provides important insights into the molecular mechanisms that mediate TGF-β1-up-regulated CTGF expression in human granulosa cells.

Human chorionic gonadotropin improves endometriosis through downregulation of leptin expression in rats

OBJECTIVE

To investigate whether and how human chorionic gonadotropin (HCG) treatment ameliorates endometriosis in an endometriotic rat model.

METHODS

Twenty-four endometriosis rats were established and were randomly divided into four groups, and then the rats were treated with 19.4, 25.8, and 51.6 IU/100 g weight/day of HCG, respectively. The control group was treated with 0.9% NaCl. After 15 days (3 estrous cycles), the ectopic lesion volume and the expression of leptin protein in eutopic and ectopic endometrium were investigated.

RESULTS

After HCG treatment, the volumes of endometriotic lesions were significantly smaller than those before treatment. During endometriosis development, the expression of leptin protein in eutopic and ectopic endometrium was remarkably increased. HCG administration reversed leptin upregulation in endometriotic tissues.

CONCLUSION

HCG therapy appears to be an effective treatment for endometriosis in rats through down-regulation of leptin expression in eutopic and ectopic endometrium.

Inhibitory effect of insulin-like growth factor-binding protein-7 (IGFBP7) on in vitro angiogenesis of vascular endothelial cells in the rat corpus luteum

Angiogenesis in the developing corpus luteum (CL) is a prerequisite for establishment and maintenance of an early pregnancy. To explore the physiological significance of insulin-like growth factor-binding protein-7 (IGFBP7) in the developing CL, the effects of IGFBP7 on vascular endothelial growth factor (VEGFA)- and luteinizing hormone (LH)-induced in vitro tube formation were tested using isolated luteal microvascular endothelial cells (LECs). Capillary-like tube formation of LECs and their proliferation were stimulated by both VEGFA and LH. IGFBP7 treatment suppressed VEGFA- or LH-induced tube formation. The proliferation and migration of LECs, and phosphorylation of mitogen-activated protein kinase kinase and extracellular signal-regulated kinase 1/2 were inhibited by IGFBP7. Furthermore, IGFBP7 attenuated VEGFA-enhanced cyclooxygenase (COX)-2 mRNA expression and prostaglandin E₂ secretion. These findings suggest the possibility that luteal IGFBP7 secretion may suppress the stimulatory effect of VEGFA on angiogenesis in the early CL.

Role of pigment epithelium-derived factor in the reproductive system

The physiological function of the female reproductive organs is hormonally controlled. In each cycle, the reproductive organs undergo tissue modifications that are accompanied by formation and destruction of blood vessels. Proper angiogenesis requires an accurate balance between stimulatory and inhibitory signals, provided by pro- and anti-angiogenic factors. As with many other tissues, vascular endothelial growth factor (VEGF) appears to be one of the major pro-angiogenic factors in the female reproductive organs. Pigment epithelium-derived factor (PEDF) is a non-inhibitory member of the serine protease inhibitors (serpin) superfamily, possessing potent physiologic anti-angiogenic activity that negates VEGF activity. The role of PEDF in decreasing abnormal neovascularization by exerting its anti-angiogenic effect that inhibits pro-angiogenic factors, including VEGF, has been investigated mainly in the eye and in cancer. This review summarizes the function of PEDF in the reproductive system, showing its hormonal regulation and its anti-angiogenic activity. Furthermore, some pathologies of the female reproductive organs, including endometriosis, ovarian hyperstimulation syndrome, polycystic ovary syndrome, and others, are associated with a faulty angiogenic process. This review illuminates the role of PEDF in their pathogenesis and treatment. Collectively, we can conclude that although PEDF seems to play an essential role in the physiology and pathophysiology of the reproductive system, its full role and mechanism of action still need to be elucidated.

Isolation of endothelial cells and pericytes from swine corpus luteum

From an angiogenesis perspective, the ovary offers a unique opportunity to study the physiological development of blood vessels. The first purpose of this work was to set up a protocol for the isolation of pig corpus luteum endothelial cells, which were characterized by both morphologic parameters and the expression of typical molecular markers; we also verified their ability to form capillary-like structures in a 3-dimensional matrix, their response to hypoxia and their migration in the presence of vascular endothelial growth factor (VEGF). The effectiveness of our isolation protocol was confirmed by the characteristic "cobblestone shape" of isolated cells at confluence as well as their expression of all the examined endothelial markers. Our data also showed a significant cell production of VEGF and nitric oxide. Isolated endothelial cells were also responsive to hypoxia by increasing the expression and production of VEGF and decreasing that of nitric oxide. In the angiogenesis bioassay, cells displayed the ability of forming capillary-like structures and also exhibited a significant migration in the scratch test. Our data suggest that the isolation of luteal endothelial cells represents a promising tool in experiments designed to clarify the biology of the angiogenic process. Furthermore, we have demonstrated that the isolated population comprises a subset of cells with a multidifferentiative capacity toward the chondrocytic and adipocytic phenotypes. These data suggest the presence of a perivascular or adventitial cell niche in the vascular wall of the corpus luteum populated with cells showing mesenchymal stem cell-like features, as already demonstrated for the adipose tissue and endometrium.

The role of the CCN family of proteins in female reproduction

The CCN family of proteins consists of six high homologous matricellular proteins which act predominantly by binding to heparin sulphate proteoglycan and a variety of integrins. Interestingly, CCN proteins are regulated by ovarian steroid hormones and are able to adapt to changes in oxygen concentration, which is a necessary condition for successful implantation. CCN1 is involved in processes of angiogenesis within reproductive systems, thereby potentially contributing to diseases such as endometriosis and disturbed angiogenesis in the placenta and fetus. In the ovary, CCN2 is the key factor for follicular development, ovulation and corpora luteal luteolysis, and its deletion leads to fertility defects. CCN1, CCN2 and CCN3 seem to be regulators for human trophoblast proliferation and migration, but with CCN2 acting as a counterweight. Alterations in the expression of these three proteins could contribute to the shallow invasion properties observed in preeclampsia. Little is known about the role of CCN4-6 in the reproductive organs. The ability of CCN1, CCN2 and CCN3 to interact with numerous receptors enables them to adapt their biological function rapidly to the continuous remodelling of the reproductive organs and in the development of the placenta. The CCN proteins mediate their specific cell physiological function through the receptor type of their binding partner followed by a defined signalling cascade. Because of their partly overlapping expression patterns, they could act in a concert synergistically or in an opposite way within the reproductive organs. Imbalances in their expression levels are correlated to different human reproductive diseases, such as endometriosis and preeclampsia.

Hormonal regulation of pigment epithelium-derived factor (PEDF) in granulosa cells

Angiogenesis is critical for the development of ovarian follicles. Blood vessels are abrogated from the follicle until ovulation, when they invade it to support the developing corpus luteum. Granulosa cells are known to secrete anti-angiogenic factors that shield against premature vascularization; however, their molecular identity is yet to be defined. In this study we address the physiological role of pigment epithelium-derived factor (PEDF), a well-known angiogenic inhibitor, in granulosa cells. We have shown that human and mouse primary granulosa cells express and secrete PEDF, and characterized its hormonal regulation. Stimulation of granulosa cells with increasing doses of estrogen caused a gradual decrease in the PEDF secretion, while stimulation with progesterone caused an abrupt decrease in its secretion. Moreover, We have shown, by time- and dose-response experiments, that the secreted PEDF and vascular endothelial growth factor (VEGF) were inversely regulated by hCG; namely, PEDF level was nearly undetectable under high doses of hCG, while VEGF level was significantly elevated. The anti-angiogenic nature of the PEDF secreted from granulosa cells was examined by migration, proliferation and tube formation assays in cultures of human umbilical vein endothelial cells. Depleting PEDF from primary granulosa cells conditioned media accelerated endothelial cells proliferation, migration and tube formation. Collectively, the dynamic expression of PEDF that inversely portrays VEGF expression may imply its putative role as a physiological negative regulator of follicular angiogenesis.

Role of hCG in vasculogenic mimicry in OVCAR-3 ovarian cancer cell line

OBJECTIVES

Vasculogenic mimicry (VM) is induced by hypoxia in 3-dimensional culture of ovarian cancer cells. By using this 3D model system, we explored the expression of human chorionic gonadotropin (hCG) and its effects on VM formation in ovarian cancer cell line OVCAR-3 both under normoxic and hypoxic conditions.

METHODS

Vasculogenic mimicry was identified by morphological observation and detection of vascular cell marker expressed by OVCAR-3. Potential formation of tumor channels was observed by light microscopy and scanning electron microscopy. Expression of vascular cell marker CD31, vascular endothelial growth factor, and Factor VIII were detected by flow cytometry, immunochemistry, and Western blot. Expression of hCG was investigated by enzyme-linked immunosorbent assay, chemiluminescence immunoassay, real-time polymerase chain reaction (PCR), and Western blot. Expression of hypoxia-inducible factor-1α (HIF-1α) was detected by real-time PCR, Western blot, and blocked by small interference RNA. Incubation of OVCAR-3 with recombinant hCG was used to evaluate its effect on VM formation. The specificity of the effect of hCG was assessed by inhibition with the neutralizing anti-hCG antibody.

RESULTS

OVCAR-3 cells formed vessel-like network structures and expressed vascular marker significantly under hypoxia in 3D. The expression level of hCG under hypoxia was significantly higher than that under normoxia. Attenuating hypoxia-inducible factor (HIF)-1α expression via small interference RNA resulted in a significantly decreased hCG expression in OVCAR-3, which indicated that the effect of hypoxia on hCG expression was mediated through HIF-1α. Treatment of OVCAR-3 with 5000 mU/mL hCG resulted in the presence of tumor cell-lined vasculature and significant elevation in vascular marker expression, even under normoxia. Expression level of vascular marker and HIF-1α in OVCAR-3 increased in response to hCG treatment in a dose-dependent manner. The effect of hCG was inhibited by the neutralizing anti-hCG antibody.

CONCLUSIONS

Human chorionic gonadotropin has the potential to induce VM in OVCAR-3. Human chorionic gonadotropin might have synergistic hypoxia-induced effect on vascular marker and HIF-1α expression.

Angiogenesis and vascular function in the ovary

Ovarian function is dependent on the establishment and continual remodelling of a complex vascular system. This enables the follicle and/or corpus luteum (CL) to receive the required supply of nutrients, oxygen and hormonal support as well as facilitating the release of steroids. Moreover, the inhibition of angiogenesis results in the attenuation of follicular growth, disruption of ovulation and drastic effects on the development and function of the CL. It appears that the production and action of vascular endothelial growth factor A (VEGFA) is necessary at all these stages of development. However, the expression of fibroblast growth factor 2 (FGF2) in the cow is more dynamic than that of VEGFA with a dramatic upregulation during the follicular–luteal transition. This upregulation is then likely to initiate intense angiogenesis in the presence of high VEGFA levels. Recently, we have developed a novel ovarian physiological angiogenesis culture system in which highly organised and intricate endothelial cell networks are formed. This system will enable us to elucidate the complex inter-play between FGF2 and VEGFA as well as other angiogenic factors in the regulation of luteal angiogenesis. Furthermore, recent evidence indicates that pericytes might play an active role in driving angiogenesis and highlights the importance of pericyte–endothelial interactions in this process. Finally, the targeted promotion of angiogenesis may lead to the development of novel strategies to alleviate luteal inadequacy and infertility.

Regulation of soluble vascular endothelial growth factor receptor 1 secretion from human endothelial cells by tissue inhibitor of metalloproteinase 1

Vascular endothelial growth factor (VEGF) and its soluble receptor (sVEGFR-1) are key regulators in human ovarian angiogenesis. Produced by granulosa and ovarian theca interna cells, VEGF promotes blood vessel growth during follicular development and corpus luteum formation, whereas sVEGFR-1, which is secreted by endothelial cells, functions as an antagonist to VEGF activity by binding it. In order to gain further insights into the regulatory mechanisms of ovarian angiogenesis, the aim of the present study was to analyze the influence of tissue inhibitor of metalloproteinase 1 (TIMP-1), which is actively involved in the degradation and remodeling of the extracellular matrix, on sVEGFR-1 secretion of cultured human umbilical vein endothelial cells. sVEGFR-1 production was determined in the culture supernatant by Sandwich-ELISA. We showed that TIMP-1 produced by human granulosa cells and recombinant human TIMP-1 both significantly increased the production of sVEGFR-1 in endothelial cells. Also, the down-regulation of TIMP-1 expression by RNA interference resulted in a significant reduction of endothelial sVEGFR-1 secretion into the culture medium. Furthermore, TIMP-1 weakly inhibited proliferation of VEGF-stimulated endothelial cells. In conclusion, our results provide evidence that TIMP-1 increases the production of sVEGFR-1 in endothelial cells and thus may reduce VEGF bioavailability, leading to reduced blood vessel growth in the ovary.

[Role of implantation-related factors, stathmin and insulin-like growth factor-binding protein 7 in reproductive endocrinology]

Successful implantation and placentation require that trophoblasts adhere to the uterine epithelium and penetrate the decidualized endometrium. However, the biochemical mechanisms of the establishment of pregnancy including these phenomena have not yet to be definitively elucidated. We have found that stathmin, a cytosolic phosphoprotein that regulates microtubule dynamics, and insulin-like growth factor-binding protein (IGFBP)-related protein 1 (IGFBP-rP1, now called IGF-binding protein 7) were highly expressed in the endometrium around the time of implantation and decidualization. In this article, we review our recent findings of the research regarding the functions of these implantation-associated proteins in endocrine physiology and pharmacology. Analysis of the expression of both factors in rodent and human uterus has revealed that both factors are crucial for the process of endometrial stromal cell differentiation.

Effect of Insulin-Like Growth Factor-Binding Protein 7 on Steroidogenesis in Granulosa Cells Derived from Equine Chorionic Gonadotropin-Primed Immature Rat Ovaries

Insulin-like growth factor (IGF)-binding protein (IGFBP) 7 is a secreted protein that regulates cellular proliferation, adhesion, and angiogenesis, and has low affinity for IGF compared with that of IGFBP1-IGFBP6. We sought to determine whether IGFBP7 is present in follicular fluid and to elucidate whether IGFBP7 participates in the steroidogenesis of rat mature follicles. Follicular fluid and granulosa cells (GCs) were collected from immature rats 2 days after their treatment with equine chorionic gonadotropin (eCG). IGFBP7 protein was detected in the follicular fluid and the conditioned medium of cultured ovarian GCs by immunoblot analysis. When subconfluent GCs were cultured and treated with FSH and activin, coincubation with FSH and activin markedly increased GC expression of Cyp19a1 (aromatase) mRNA and 17beta-estradiol (E(2)) secretion. The addition of recombinant murine IGFBP7 to these cultures decreased in the activin-enhanced, FSH-stimulated Cyp19a1 mRNA levels in the cells and suppressed the 17beta-E(2) levels in the culture medium. Treatment of GCs with Igfbp7-specific small interfering RNA (siRNA), which knocked down Igfbp7 expression, increased the FSH-stimulated levels of Cyp19a1 but not Cyp11a1 expression. Basal and FSH-stimulated 17beta-E(2) secretion into the culture medium was also enhanced by Igfbp7 siRNA. These results suggest that IGFBP7 suppresses estrogen production in GCs. These observations support the notion that this protein, which is secreted into the follicular fluid, may serve as an intraovarian factor that negatively regulates GC differentiation.

The 3D vascular status of the follicle after HCG administration is qualitatively rather than quantitatively associated with its reproductive competence

BACKGROUND

The objective of this study was to determine whether the vascular status of a single pre-ovulatory follicle is associated quantitatively and/or qualitatively with its reproductive competence.

METHODS

We studied 61 monofollicular IVF-embryo transfer cycles. Just before single oocyte retrieval, follicle vascularization was detected by transvaginal power-Doppler, 3-dimensionally reconstructed, and analysed quantitatively by coloured/gray voxel ratio [vascularization index (VI)] and qualitatively by blood cell displacement [flow index (FI)] calculation. Cycles were sorted in two sets of two groups: low VI (<or=8%, n = 44) and high VI (>8%, n = 17); low FI (<or=30, n = 22) and high FI (>30, n = 39).

RESULTS

Patients' characteristics, fertilization rates, and embryo morphology were comparable in all groups. In contrast, clinical pregnancy rates/oocyte retrieval (4% versus 33%, P < 0.009) and implantation rates (11% versus 50%, P < 0.04) were markedly poorer in the low as compared to the high FI groups, respectively, but remained similar between the low and the high VI groups (22% versus 23% and 38% versus 44%, respectively).

CONCLUSIONS

A qualitative (FI) rather than quantitative (VI) relationship exists between vascular status and functional quality of the follicle after HCG administration.