Integrins are not involved in the process of human sperm-oolemmal fusion

BACKGROUND: We investigated whether integrins are required forthe human sperm–oocyte binding and fusion processes. METHODS:The expression of several integrin subunits at the human oocyteplasma membrane was investigated using immunofluorescence microscopy,and the functional role of integrins expressed at the humanoocyte surface in sperm–oocyte interaction was studiedusing a zona-free human oocyte binding and fusion assay. A totalof 144 unfertilized oocytes were stained with anti-integrinantibodies and 147 zona-free unfertilized oocytes were inseminatedin the presence of various anti-integrin antibodies that wereexpressed in oocyte plasma membrane. RESULTS: The antibodiesof six integrin subunits (₂, ₃, ₅, ₆, _V, _M) and six integrinsubunits (₁, ₂, ₃, ₄, ₅, ₆) were bound to the surface of fixedunfertilized oocytes. In contrast, the presence of ₁ and ₄ subunitscould not be verified. The human sperm–oocyte bindingwas only partially inhibited by blocking antibodies of ₂, ₃,₅, ₆, _V, _M, ₁, ₂ and ₃ with a maximum of 55% inhibition, butantibodies of ₄, ₅ and ₆ showed no effect on sperm–oolemmalbinding. A similar reduction of the number of fused sperm wasobserved. However, the ratio of fused sperm to total sperm (boundand fused) was not impaired by all integrin antibodies, suggestingthat integrins had no role in the sperm–oolemmal fusionprocess. CONCLUSIONS: These results suggest that one of thebinding mechanisms can be inhibited by integrin antibodies butthat this mechanism does not play an essential role in the humansperm–oolemmal binding and fusion processes. The othermechanisms, insensitive to integrins, may involve both bindingand fusion processes in human oocytes.     

Concentration of interleukin-1{beta} correlates with prostaglandin E2 and F2{alpha} in human pre-ovulatory follicular fluid

To investigate the role(s) of interleukin-1 (IL-1) in humanovarian function, we measured the concentrations of IL–1,prostaglandins (PGs) and steroids in follicular fluid of 90stimulated ovaries, with reference to oocyte maturation. Concentrationsof IL-1 were significantly higher in the follicles from whichmature oocytes were recovered than in follicles from which oocytescould not be recovered (P < 0.05). IL-1 concentrations alsoincreased in association with oocyte maturation. Positive significantcorrelations were seen between IL-1 and prostaglandin E2 (PGE2)(r = 0.47, P < 0.001), and between IL-1 and prostaglandinF₂ (PGF₂) (r = 0.22, P < 0.05) in pre-ovulatory follicularfluid, but not between IL–1 and oestradiol, or betweenIL-1 and oestradiol, or between IL-1 and progesterone. 0Follicularfluid IL-1 might contribute to prostaglandin-induced oocytematuration and ovulation.     

Molecular aspects of implantation: Human trophoblast adhesion to matrix proteins: inhibition and signal transduction

At the time of implantation, the extracellular matrix proteinslaminin and fibronectin are abundant in the decidua and aredistributed pericellularly around each individual stromal cell.First trimester human trophoblast expresses both laminin andfibronectin receptors, specifically the ₁₁, ₅₁, ₆₁ and ₆₄ integrinheterodimers. In this study we have demonstrated that in-vitroadhesion of first trimester human trophoblast to purified extracellularmatrix proteins and to purified decidual stromal cell monolayerscan be inhibited by monoclonal antibodies directed against appropriateintegrin subunits and by synthetic peptides containing an arginine-glycine-asparticacid sequence. Monoclonal antibodies (mAbs) to the ₅ and ₁ integrinsubunits and a synthetic peptide significantly inhibited adhesionto fibronectin. Binding of trophoblast to laminin was blockedwith mAbs to the ₆ and ₁ but not ₁ and ₄ integrin subunits.Similarly, integrin-mediated adhesion to monolayers of decidualstromal cells could be blocked with mAbs to the ₅, ₆, ₁ and₄ integrin subunits. Integrin-mediated signal transduction innormal and malignant trophoblast was investigated by Westernblotting. A 115 kDa protein was the major tyrosine phosphorylatedprotein detected in trophoblast after binding to laminin orfibronectin. The profile of tyrosine phosphorylated proteinsdiffered for malignant trophoblast.     

Endocrinology: Substrate dependency of C19 conjugates in hirsute hyperandrogenic women and the influence of adrenal androgen

Serum C₁₉ conjugates, specifically 3-androstanediol glucuronide(3G), reflect peripheral androgen action through the actionof 5-reductase activity. The origin of 5-reduced C₁₉ conjugateshas been controversial and it has been suggested that they arederived primarily from adrenal androgens. We examined concentrationsof 3G, 3-androstanediol sulphate (3S), androsterone glucuronide(AoG) and androsterone sulphate (AoS) in 40 hirsute hyperandrogenicwomen. These patients were divided into four groups based uponindividual, combined or normal concentrations of the adrenalandrogens dehydroepiandrosterone (DHEAS) and 11-hydroxy-androstenedione.Testosterone, unbound testosterone and androstenedione weresimilar in these groups. Serum 3G was equally high in all groupsand was correlated significantly with hirsutism, while the otherconjugates were not. Androsterone glucuronide was raised inall groups but was higher in patients with raised DHEAS. Serum3S was raised in all groups and was higher where both adrenalandrogens were raised. Serum AoS was highly correlated withDHEAS. Serum 3G was correlated with unbound testosterone andandrostenedione but not with the adrenal androgens. The glucuronideconjugates were correlated with one another as were the sulphateconjugates but glucuronides and sulphates were not correlated.These data confirm ovarian and adrenal dependency of C₁₉ conjugates.Serum 3G appears to reflect hirsutism most accurately and isleast dependent on adrenal androgens in patients with mixedhyperandrogenism.     

Endocrinology: Prostaglandin F2{alpha} stimulates release of insulin-like growth factor binding protein-3 from cultured human granulosa-luteal cells

Human ovarian follicular fluid contains a number of insulin-likegrowth factor binding proteins (IGFBP) of which IGFBP-3 is themost abundant. IGFBP-3 synthesis is growth hormone-regulated.We studied the effect of prostaglandin F₂ (PGF₂) on IGFBP-3secretion by cultured human granulosa-luteal cells from follicularaspirates of women participating in an in-vitro fertilizationprogramme. The IGFBP-3 concentration was measured using a specificmonoclonal immunofluorimetric assay. Contrary to a previousreport on unstimulated follicles, this study demonstrated apositive correlation between follicular fluid IGFBP-3 concentrationand follicular size. PGF2a was found to stimulate in a dose-dependentfashion the secretion of IGFBP-3. Significant (p < 0.05)effects were found at PGF₂ concentrations of 10^–8, 10^–7and 10^–6 M. Because IGFBP-3 inhibits progesterone productionstimulated by insulin-like growth factor (IGF)-I, the PGF₂-inducedstimulation of IGFBP-3 production may be one of the mechanismswhereby PGF₂ exerts its luteolytic effect via the IGF system     

Ovary: Immunolocalization of transforming growth factor-{beta}1 and transforming growth factor-{beta}2 in the mouse ovary during gonadotrophin-induced follicular maturation

An immunohistochemical approach was utilized to evaluate thecellular distribution of transforming growth factor-₁ (TGF₁)and transforming growth factor ₂ (TGF₂) at different stagesof follicle development in the prepubertal mouse ovary underthe following conditions: (i) after pregnant mare's serum gonadotrophin(PMSG) treatment; (ii) after PMSG and human chorionic gonadotrophin(HCG) treatment; (iii) after PMSG and HCG treatment plus mating.In the immature ovary, TGFF₁ and TGF₂ immunoreactivities arelocalized in theca and granulosa cells and in oocytes. AfterPMSG treatment, TGF₁ and TGF₂ immunoreactivities are localizedin granulosa cells; in addition, TGF₂ staining is noted in thematrix surrounding antral cells. Staining for both TGF₁ andTGF₂ drops in the theca but persists in the oocyte. PMSG plusHCG treatment results in a significant increase in TGF₁ andTGF₂ immunoreactivity in the theca and in the maintenance ofTGF₁ staining in both basal granulosa cells and cumulus cellswhereas TGF₂ immunoreactivity is essentially localized in thematrix surrounding cumulus cells. Staining for TGF₁ and TGF₂persists in the oocyte. Following PMSG plus HCG treatment andmating, TGF₁ immunoreactivity is localized in the luteal cellsof corpora lutea and TGF₂ shows a similar localization pattern.This study provides evidence that TGF₁ and TGF₂ peptides areexpressed in specific cell types during induced follicular maturationin the mouse ovary.     

Stimulation of prostaglandin (PG) F2{alpha} and PGE2 release by tumour necrosis factor-{alpha} and interleukin-1{alpha} in cultured human luteal phase endometrial cells

Tumour necrosis factor- (TNF-) and interleukin-1 (IL-1) areimportant mediators of cell signalling in the uterus. Prostaglandins(PG) have been implicated in the increase of endometrial vascularpermeability which occurs during the implantation process. Thisstudy evaluates the effect of these two pleiotropic cytokineson PGF₂ and PGE₂ release from human luteal phase endometrialglandular epithelial cells (GEC) and stromal cells (STC) inculture. Basal PGF and PGE release did not differ significantlyfrom each other or among cell types, and declined significantlywith increasing number of days in culture. On day 3, basal PGrelease had decreased to half of that on day 1 of culture. However,both cell types were still able to respond to the addition ofexogenous arachidonic acid (5 µM) on day 3 of culture,with PG release by GEC being elevated 7- to 10-fold and by STCmoderately, but still significantly, on day 4. The permissiveeffect of arachidonic acid on the stimulation of PG releasemay indicate the down-regulation of phospholipase A₂ with continuedtime in culture. However, the addition of arachidonic acid (5µM) on day 0 of culture, while able to cause significantlyincreased PG release from GEC, had no effect on STC. In contrast,the addition of a combination of arachidonic acid (5 µM),and either recombinant human TNF- (10 µg rhTNF-/I) or10 µg rhlL-1/I, had a synergistic action and caused thesignificantly increased release of PGF and PGE from both celltypes, compared with that achieved with either arachidonic acidor the cytokine alone (although GEC responded more than STC).During the first 24 h after the addition of rhTNF- or rhlL-1,both cytokines stimulated PG release from both cell types ina dose- and time-dependent fashion. Neither cycloheximide (10µM) nor actinomycin D (10 µM) affected basal PGrelease, but both blocked cytokine-induced PG release from bothcell types. These results suggest that there is a differentialcontrol of human endometrial cell PG biosynthesis, and thatPG release may be regulated through gene activation.     

Integrins and adhesion mlecules: Cell adhesion molecules on the oocyte and preimplantation human embryo

The presence of cell adhesion molecules on human oocytes, earlyembryos, and pre-hatched blastocysts was examined by indirectimmunofluorescence and compared to the distribution found onfirst trimester villous placenta with the same antibodies. Sixintegrin subunits (3, V, 1, 3, 4, 5) were observed consistentlythroughout preimplantation development. Evidence was also obtainedfor the presence of integrin subunits 2, 4, L, 2, and 7 on asmall number of oocytes. A more restricted developmental analysisof E-cadherin, ICAM-1, NCAM, and VCAM-1 demonstrated that thesecell adhesion molecules are also present on oocytes and earlyembryos. L-selectin was detected on oocytes but was not foundon 8-cell embryos. The oocyte and early blastomeres have complexsurfaces in which the integrin and CAM families are represented.     

Interleukin-1{alpha} and -{beta} modulation of luteinized human granulosa cell oestrogen and progesterone biosynthesis

This study was designed to test the hypothesis that inter-leukin-1(IL-1) and directly affect progesterone, and oestradiol productionin cultures of purified human granulosa cells. Luteinized granulosacells were obtained from women during in-vitro fertilizationcycles. Granulosa cells with and without associated white bloodcells were cultured in the presence of IL-1 and IL-1 (0.5–50ng/ml) for 48 h. Media were changed at 24 h intervals and assayedfor progesterone and oestradiol. In separate experiments, granulosacell viability was assessed with the tetrazolium salt reductionassay, haemocytometer cell counts, and Trypan blue dye exclusion.Our results indicate that progesterone synthesis by basal andhuman chorionic gonadotrophin (HCG)-stimulated granulosa cellsco-cultured with white blood cells was inhibited by 5.0 ng/mlof IL-1 and IL-1 at 48 h of culture. In the presence of whiteblood cells, granulosa cell oestradiol synthesis was inhibitedby IL-1 but not IL-1. Oestradiol was inhibited after both 24and 48 h of culture and was maximally affected by 5.0 ng/mlof IL-1. In contrast, basal and HCG-stimulated oestradiol productionby granulosa cells cultured free of white blood cells was inhibitedonly by IL-1. IL-1 at 5.0 ng/ml produced maximal inhibitionof basal oestradiol (57%) and HCG-stimulated oestradiol (41%)production at 48 h of culture. Gonadal steroid inhibition byIL-1 and IL-1 was not mediated through cytotoxic or antiproliferativeeffects on granulosa cells. Specificity of the granulosa cellresponse to IL-1 and IL-1 was demonstrated by abrogation ofsteroid inhibition with anti-IL-1 and IL-1 neutralizing antibodies.In conclusion, IL-1 directly inhibited the production of oestradiolby human ovarian granulosa cells. IL-1 and IL-1 also exertedindirect effects on steroid production via white blood cellsthat are usually present in granulosa cell cultures if stepsare not taken to remove them. These data support the hypothesisthat cytokines play an important role in intra-ovarian regulationof steroid biosynthesis.     

Pregnancy: Effect of the vascular endothelium on contractions induced by prostaglandin F 2{alpha}in isolated pregnant guinea pig uterine artery

The purpose of this study was to examine the influence of endotheliumon prostaglandin F₂-mediated contractions in pregnant guineapig uterine artery. Consequently, the effects of prostaglandinF₂ pregnant guinea pig uterine arterial rings with both Intactand denuded endothelium were studied. In vessels with denudedendothelium prostaglandin F₂ (0.1–10 µM) inducedcontraction (pD₂ = 6.17) with greater potency than in vesselswith intact endothelium (pD₂ 5.68). N^G.Monomethyl (10 µM)did not affect the concentration—response curve for prostaglandinF₂ regardless of endothelial condition. In contrast, in bothtypes of preparation, indomethacin (10 µM) increased themaximal response value obtained with prostaglandin F₂ but thiseffect was significantly greater in preparations with intactthan In those with denuded endothelium (128.3 versus 206.5%).Moreover, indomethacin shifted the concentra tion-response curvefor prostaglandin F2 to the left only in preparations with intactendothelium. The PK_A values for prostaglandin F₂ itself didnot differ between preparations: 5.41 and 5.52 for pregnantguinea pig uterine artery with and without endotheliuin, respectively.The receptor reserve expressed as K_A/EC₅₀ was significantlygreater in rings with denuded (4.44) compared to those In ringswith intact endo thelium (1.86). We conclude that prostaglandin-F₂contraction in pregnant guinea pig uterine artery is modu latedby the vascular endothelium. It is probable that cyclo oxygenaseproducts relating to vasodilatation and derived from endotheliummediate this effect, acting as a functional endogenous antagonistand thereby reducing the apparent efficacy and potency of prostaglandinF₂     

Expression of integrins by human trophoblast and differential adhesion to laminin or fibronectin

The process of placental implantation involves a series of transformationsof trophoblast from a single polarized epithelial layer restingon a basement membrane (villous trophoblast), to cellular aggregates(trophoblast columns) which ultimately disperse to invade uterinedecidua as individual cells (interstitial trophoblast). Suchtissue re-modelling is associated with changes in the constituentsof the extracellular matrix and in the expression of matrixreceptors by the cells, the most relevant being the family ofintegrins which bind to laminin and fibronectin. In this studywe show, by immunohistology and flow cytometry, a gradual lossof laminin receptors with the concomitant acquisition of fibronectinreceptors as trophoblast is transformed from the villous phenotype,through the cell columns, into the extravillous population.The pattern of staining for the ₅, ₆, ₁ and ₄ subunits indicatesthat the integrins expressed by trophoblast are predominantlythe ₅₁ and the ₆₄ heterodimers. We have also shown that isolatedtrophoblast cells assume a flattened, sessile phenotype whencultured on laminin but exhibit a more spreading, motile morphologywhen plated on fibronectin. In addition, numerous multinucleatedgiant cells are observed on a fibronectin substrate. Our datasuggest that the relative expression of laminin and fibronectinreceptors may determine the morphology and behaviour of trophoblastduring the process of implantation.     

Ovary and ovulation: Interaction between oxytocin and prostaglandin F2{alpha} in human corpus luteum?

The effect of a single injection of oxytocin into the corpusluteum, with or without pretreatment with a prostaglandin synthetaseinhibitor, was studied in order to investigate possible localinteractions between prostaglandin (PG)F₂ and oxytocin in theregulation of the human corpus luteum. Oxytocin (4 IU) was injectedthrough the abdominal wall into the corpus luteum in women undergoinglaparoscopy for legal sterilization. In the control cases, salinewas injected into the corpus luteum, or oxytocin was injectedinto the contralateral ovary. Oxytocin injected into the corpusluteum caused a fall in serum progesterone and shortened theluteal phase. These effects were not seen following injectionof saline into the corpus luteum, or following injection ofoxytocin into the contralateral ovary. After the injection ofoxytocin into the corpus luteum a rise in 15-keto-dihydro-PGF₂,a PGF₂ metabolite, was seen. The changes in serum progesteronecaused by injection of oxytocin into the corpus luteum couldbe prevented if a PG synthetase inhibitor was given before theinjection. These findings suggest that local interaction betweenoxytocin and PGF₂ plays a role in the regulation of the humancorpus luteum.     

Immunology: {beta}2-Glycoprotein I-dependent and -independent anticardiolipin antibodies in healthy pregnant women

The purpose of this study was to determine the association between₂-glycoprotein I (₂GPI)-dependent anticardiolipin antibodies(aCL) and ₂GPI-independent aCL and their respective relevanceto adverse pregnancy outcomes. Therefore, we prospectively studied210 normal pregnant women, utilizing a modified enzyme-linkedimmunosorbent assay method for ₂GPI-dependent and -independentaCL. Seven of the 210 pregnant women (3.3%) demonstrated evidencefor ₂GPI-independent immunoglobulin G (IgG)-aCL. Two patients,who also appeared positive for ₂GPI-dependent IgG-aCL, wereproven to be false positives. Amongst the 210 patients, notone was thus positive for ₂GPI-dependent aCL. Women with ₂GPI-independentaCL demonstrated no adverse pregnancy outcomes. These resultssuggest that the presence of ₂GPI-independent aCL is not associatedwith the presence of 2GPI-dependent aCL, though it may giverise to false positive results. Since the presence of 2GPI-independentaCL does not appear to be associated with adverse pregnancyoutcomes, ₂GPI-dependent assays may represent better markersof miscarriage risk.     

Follicular fluid prostaglandin E2:prostaglandin F2{alpha} ratio in relation to outcome of matched oocyte

The prostaglandins PGE₂ and PGF₂ and the steroid hormones oestradiol(E₂) and progesterone (P) were measured in 345 follicular fluidsof patients undergoing ovarian hyperstimulation for in-vitrofertilization (IVF). The measured concentrations were analysedin relation to the outcome of the matched oocyte. Progesteronelevels were significantly tower in the unfertilized group (P<0.005)compared to the fertilized group but there was no differencebetween ‘pregnancy’ and ‘no pregnancy’.No differences were shown in either E₂ levels or the E₂:P ratio.No significant differences were shown among the groups in theconcentration of either PGE₂ or PGF₂ but there were highly significantdifferences shown when the PGE₂:PGF₂ ratios were compared. ThePGE₂:PGF₂ ratio fell within a much narrower range for the ‘pregnancy’group compared with any of the other groups. The ratio was significantlylower (P<0.001) when ‘pregnancy’ was comparedwith ‘no pregnancy’. The range of the prostaglandinratio found for the ‘pregnancy’ group may reflectthe moment when conditions are optimal within the follicle forthe associated oocyte to go on to establish pregnancy.     

Implantation: Impact of trophoblast penetration through the basal membrane on the efficacy of drug therapy in tubal pregnancies

Concentrations of -human chorionic gonadotrophin (HCG) of 2500IU/l are generally considered to be maximal for successful drugtherapy of tubal pregnancies [instillation of prostaglandin-F₂(PGF₂) or hyperosmolar glucose]. The purpose of our study wasto ascertain if there was an association between the significantlyhigher failure rates above this threshold value and the histologicallydetermined anatomopathological substratum. We therefore evaluatedthe impact of trophoblast penetration through the basal membraneof the Fallopian tube on the efficacy of drug therapy. Pre-operativeserum -HCG concentrations were compared with the histologicallydetermined trophoblast penetration, distinguishing between ectopicpregnancies with intra-luminal growths up to the myosalpinx,and those with extra-luminal growths going beyond the basalmembrane and penetrating the myosalpinx. Basic data were obtainedfrom a group of patients who received primary surgical treatmentbut it had never been the intention for them to receive drugtherapy (independently of their initial -HCG values; group I,n = 43). These reference data were compared with the findingsin preparations from another group of patients obtained duringsecondary surgical intervention, performed to achieve finalcure of tubal pregnancy after failure of primary PGF₂ instillation(group II, n = 30). Group I patients showed a significantlyhigher rate of intra-luminal trophoblast growths (P = 0.0001)at -HCG values <2500 IU/l; above this threshold value, extra-luminalspread was found significantly more often (P = 0.0001). In histologicalpreparations from group II, however, the number of extra-luminalgrowths was significantly higher even at low -HCG values (P= 0.007); at values above the threshold level, the distributionsin the two groups were similar. These results suggest that drugtherapy of tubal pregnancy becomes inefficient in tubal pregnanciesas soon as the trophoblast penetrates the basal membrane ofthe Fallopian tube.     

Immunohistological distribution of the secretory endometrial protein, 'pregnancy-associated endometrial {alpha}2-globulin', a glycosylated {beta}-lactoglobulin homologue, in the human fetus and adult employing monoclonal antibodies

We have previously demonstrated that pregnancy-associated endometrial₂-globulin (₂-PEG), the human glycosylated (-lactoglobulin homologue(HG-BLG), is quantitatively the major secretory soluble proteinproduct of the secretory endometrium during the latter halfof the menstrual cycle and decidua spongiosa of the gestationalendometrium during early pregnancy, and is principally localizedto the glandular epithelium. In the present study employingmonoclonal antibodies in immunohistological techniques, thedistribution and localization has been examined in normal andpathological tissues of the adult and first-trimester fetus.No significant staining for ₂-PEG was detected in any non-reproduction-associatedtissue in the normal adult nor any tissue in the fetus. In theadult, most intense staining was associated with the endometrialglandular epithelium in the uterus or in ectopic sites in patientswith endometriosis. During the menstrual cycle and pregnancy,appearance of ₂-PEG in endometriosis was strongly linked withits appearance in uterine endometrial tissue, suggesting thatendometriotic tissue exhibited competence to respond to thesame hormonal milieu required to induce synthesis in the uterineendometrium. Localization to the mucosal epithelium of the Fallopiantube was consistent with synthesis of ₂-PEG, albeit at low levels,and staining at this site reflected fluctuations of stainingwithin the uterus. Of the pathological specimens examined, stainingwas only detected in a proportion of ovarian carcinomas. Nostaining was detected in the mammary gland, a site of -lactoglobulinsynthesis, whether obtained during pregnancy or lactation. Theseobservations support the proposal that during the menstrualcycle and pregnancy, the endometrial glandular epithelium representsthe major source of the glycosylated -lactoglobulin homologueand serum measurements may be employed to assess its functionalpresence. Mechanisms of regulation of its production that wouldaccount for the histological observations are discussed.     

Reactive oxygen species stimulate prostaglandin F2 alpha production in human endometrial stromal cells in vitro

BACKGROUND: The present study was undertaken to investigatethe effect of reactive oxygen species on prostaglandin F2 (PGF2)production by human endometrial stromal cells (ESC). METHODSAND RESULTS: Isolated ESC were incubated with hydrogen peroxide,which induces lipid peroxidation. Hydrogen peroxide increasedboth intracellular and medium concentrations of PGF2 (P <0.01). A time course study showed that hydrogen peroxide significantlyincreased PGF2 concentrations in the medium after 6 h incubation(P < 0.01), after which no further increase was observed.To study whether the increase in PGF2 production caused by hydrogenperoxide was mediated by cyclooxygenase, ESC were incubatedwith indomethacin (0.5 µg/ml), an inhibitor of cyclooxygenase,in the presence of hydrogen peroxide. Indomethacin significantlyblocked the increases in PGF2 production caused by hydrogenperoxide (P < 0.01). Hydrogen peroxide also increased PGF2production by decidualized ESC (P < 0.01), induced by theincubation with medroxyprogesterone acetate (10^–6 mol/l)and oestradiol (10^–8 mol/l). CONCLUSIONS: Reactive oxygenspecies stimulate PGF2 production in ESC, suggesting that theymight influence endometrial function by regulating PGF2 production.     

The expression of {alpha}v and {beta}3 integrin subunits in the normal human Fallopian tube epithelium suggests the occurrence of a tubal implantation window

The co-expression of ₁ß₁, ₄ß₁ and _vß₃integrins in the human endometrium coincides with the implantationwindow. The _vß₃ integrin is expressed in the apicalsurface of the luminal epithelium and may serve to anchor trophoblastcells in the adhesion phase of implantation. Using immunohistochemistry,we compared the expression of _v, ₁, ₄ and ß₃ integrinsubunits in samples of normal human Fallopian tube and endometriumobtained from five women in the non-receptive period (lutealphase days 2–4) and from another five women in the receptiveperiod (luteal phase days 6–8). The staining was quantifiedvisually on a scale of 0 to ++, according to the intensity anddensity of stained cells. The _v subunit is expressed in theFallopian tube epithelium during both periods in a pericellulardistribution. The ß₃ subunit is also expressed inthe same location, but it is up-regulated during the periodof endometrial receptivity. The other subunits are expressedin localizations which are not relevant to trophoblast adhesionand exhibit little or no difference in the level of expressionbetween the non-receptive and receptive periods. Based on theseresults we postulate that the expression of the ß₃subunit in the human tubal epithelium is under the same systemiccontrolling signals as in the endometrium and that the normaltubal epithelium may have an implantation window, at about thesame time as the endometrium, that affords the opportunity fortrophoblast attachment should a 5–7 day embryo be undulyretained in the tube.     

Integrins and adhesion molecules: Gelatinase and oncofetal fibronectin secretion is dependent on integrin expression on human cytotrophoblasts

Collagenolytic activity of cytotrophoblasts is stimulated byglycoproteins of the extracellular matrix and since this stimulationcan possibly occur through integrins, we measured the gelatinolyticactivity of villous and extravillous cytotrophoblasts accordingto the type of integrins expressed on these cells. Cytotrophoblastswere isolated from legal abortions, immunopurified with anti-CD45,separated according to their expression of histocompatibility-linkedantigen (HLA)-G, ₆ or ₅ integrin subunits and cultured for 5days on plastic or agarose. Fetal fibronectin, human chorionicgonadotrophin (HCG) and the gelatinolytic activity were measuredin the culture supernatants. Following immunopurification withanti-CD45, the gelatinolytic activity of cytotrophoblasts wassignificantly higher than before, indicating that contaminatinglymphomyeloid cells secreted gelatinolytic inhibitors. HLA-Gpositive cells secreted significantly more gelatinases thanHLA-G negative cells but their HCG secretion was similar. Comparedto ₅ positive cells, ₆ positive cytotrophoblasts secreted significantlymore gelatinases, significantly less fibronectin but similaramounts of HCG. We conclude that during trophoblast invasion,extravillous cytotrophoblasts (HLA-G positive) expressing the₆ integrin subunit represent the invasive population of cells(high gelatinase and low fibronectin secretion). When expressionof the ₅ integrin subunit is turned on, their invasive behaviourceases and they secrete low amounts of gelatinases and highconcentrations of fibronectin.