Molecular Human Reproduction, Vol. 6, No. 2, 170-177,
February 2000
© 2000 European Society of Human Reproduction and Embryology
Uterus and pregnancy |
Adhesion of menstrual endometrium to extracellular matrix: the possible role of integrin 
6ß1 and laminin interaction
1 Research Institute GROW, 2 Department of Obstetrics & Gynaecology, 3 Department of Pathology, Academisch Ziekenhuis Maastricht and Maastricht University, Maastricht, The Netherlands
Abstract
Previous in-vitro studies have shown that the endometrium preferentially adheres to the extracellular matrix (ECM) of the amnion and peritoneum. This interaction probably involves adhesion molecules, e.g. integrins. We evaluated the expression of integrins in naturally shed menstrual endometrium and the adhesion pattern of this tissue to different components of the ECM. To identify integrins and matrix components involved, blocking studies were performed. Most of the 15 menstrual tissue samples showed positive staining for each of the integrins investigated, except 
4ß1. Compared with binding to collagen IV, which was set at 100%, adhesion to collagen I was 93% (not significant), to fibronectin 87% (P < 0.05), and to laminin 74% (P < 0.05). Scanning electron micoscopy showed that endometrium adhered to laminin but hardly spread, whereas spreading was observed when layered on the other coatings. Compared with the control (which was set at 100%), incubation with 4B4, a monoclonal antibody against the integrin ß1 subunit, showed a significant reduction of adhesion (to ~50%; P < 0.05) when layered on laminin and a smaller reduction (to 82–86%; P < 0.05) when layered on the other three coatings. Incubation with antibody GOH3 against integrin 6ß1 resulted in a similar reduction in adhesion to laminin. Incubation with an RGD peptide significantly reduced adhesion (to 84%; P < 0.05) when plated on fibronectin. In conclusion, antegradely shed menstrual endometrium expresses various integrins. It shows preferential attachment to collagen IV and collagen I, when compared with fibronectin and laminin. Blockage of the integrin ß1 subunit resulted in greatest disruption to adhesion when layered on laminin, implying that the interaction was mediated by the 6ß1 integrin. Since this adhesion was not completely blocked, other mechanisms are likely to be involved.
blocking antibodies/cell culture/ectopic endometrium/menstruation/RGD peptide
Introduction
Endometriosis is a benign disease characterized by functional endometrial glands and stroma in ectopic locations outside the uterine cavity. It is associated with chronic pelvic pain and reproductive impairment. Although endometriosis is a frequently encountered problem in gynaecology, its pathogenesis is still poorly understood. According to the implantation theory, an important step in the pathogenesis of endometriosis is the adhesion of retrogradely shed endometrium to the peritoneum (Sampson, 1940
). We have previously demonstrated that human endometrial tissue does not adhere to intact epithelium but preferentially adheres to subepithelial structures (Van der Linden et al., 1996, 1998, Groothuis et al., 1998, Koks et al., 1999). In contrast, in a recent adhesion study with peritoneal explants (Witz et al., 1999), it was shown that endometrium can adhere to the mesothelium, however an intact layer of the mesothelium could not be identified under most (90%) of the attached endometrial fragments. The interaction between endometrial fragments and the submesothelial layer probably involves adhesion molecules which mediate cell–extracellular matrix (ECM) interactions, e.g. integrins. The expression pattern of a variety of integrins in endometrial tissue throughout the menstrual cycle has been described extensively (Tabibzadeh, 1992; Bridges et al., 1994; Lessey et al., 1994, 1996; Van der Linden et al., 1994, 1995; Rai et al., 1996; Béliard et al., 1997). Several studies have focused on the involvement of integrins in embryo implantation (Tabibzadeh, 1992; Lessey et al., 1996, 1998; Creus et al., 1998; Shiokawa et al., 1998). Based on reports on the expression of integrins in relation to endometriosis it has been postulated that endometriosis is associated with aberrant cell–cell or cell–ECM interactions (Bridges et al., 1994; Lessey et al., 1994; Van der Linden et al., 1994; Rai et al., 1996; Béliard et al., 1997; Ota and Tanaka, 1997; Hii and Rogers, 1998; Regidor et al., 1998).
Integrins mediate adhesion of cells to ECM proteins, e.g. collagen types I and IV, laminin and fibronectin. The integrins belong to a large family of transmembrane proteins and have a dimeric structure of and ß subunits. At least six of the known integrins bind to domains with the arginine-glycine-aspartic acid (RGD) sequence, whereas other integrins may recognize other amino acid sequences (Ruoslahti and Pierschbacher, 1987). Adhesion of cells to ECM proteins based on interactions with integrins can be impaired by specific blocking molecules (Gehlsen et al., 1988; Burrows et al., 1995).
The aim of this study was to further evaluate expression of integrins in naturally shed menstrual endometrium and to describe the ultrastructural aspects of its adhesion to ECM components. To identify integrins and matrix components involved in the adhesion of menstrual endometrium, we performed blocking studies using an RGD peptide and antibodies against the integrin ß1 subunit, and the integrin 6ß1.
Materials and methods
Characteristics of volunteers
All 18 volunteers had regular menstrual cycles of 25–34 days with 4–7 days of blood loss. None of them had a medical history of endometriosis or infertility, or used oral contraceptives or intrauterine copper devices (IUCDs). Mean age was 34 years (range 21–44 years). All gave written informed consent. The institutional review board and the medical ethics committee approved the study protocol.
Menstrual fluid collection
Menstrual fluid was collected with a menstrual cup for 2–3 h during the first and second day of the menstrual period. Day 1 was defined as the 24 h from the first awareness of menstrual bleeding onwards. The menstrual cup is a soft natural rubber cup (`Keeper', Den Haag, The Netherlands), which has been used in our previous studies (Koks et al., 1997). After collection, the menstrual fluid was transferred into a plastic container and immediately delivered to the laboratory.
Endometrial tissue preparations
Isolation of endometrial tissue from menstrual effluent has been described previously (Koks et al., 1997). Briefly, menstrual fluid samples were centrifuged at 600 g for 10 min. The supernatant (serum) was removed and immediately snap-frozen in isopentane immersed in dry ice. The pellet was washed with phosphate-buffered saline (PBS) and layered on a Ficoll–Paque gradient to remove red blood cells. After centrifugation at 1190 g menstrual tissue was collected from the interface. The endometrial tissue was immediately frozen in isopentane immersed in dry ice and stored at –80°C until analysed. Endometrial tissue used in adhesion and blocking assays was isolated as described above, but washes were performed with complete culture medium (CM) consisting of Dulbecco's modified Eagle's medium (DMEM)/Ham's F12 (Life Technologies BV, Breda, The Netherlands) supplemented with 10% fetal calf serum, 2 mmol/l L-glutamine and penicillin 100 IU/ml and streptomycin 100 µg/ml (Life Technologies), instead of PBS. Following the Ficoll gradient separation, menstrual tissue was washed once, resuspended in CM, filtered through a 100 µm nylon filter (Micronic, Lelystad, The Netherlands) and a 30 µm polyamide filter (Stokvis & Smits, IJmuiden, The Netherlands). The tissue fragments retained on the 100 and 30 µm filters were collected separately and resuspended in culture medium. The filtrate of the 30 µm filter was also subjected to Ficoll–Paque gradient separation to remove red blood cells from the small tissue fragments and single cells.
Immunohistochemistry
Cryostat sections of 4–6 µm were cut and mounted on gelatin-coated slides. The sections were air-dried and fixed with methanol at –20°C for 1 min, followed by an acetone dip at –20°C. Immunohistochemical staining with antibodies to integrins was performed as previously described (Van der Linden et al., 1994). A series of mouse monoclonal antibodies was used, including TS 2/7 for integrin 1ß1, IOG11 for 2ß1, J143 for 3ß1, HP2/1 for 4ß1, SAM-1 for 5ß1, LM 609 for vß3. The rat monoclonal GOH 3 for 6ß1 was used. The monoclonal antibodies TS 2/7 and LM 609 were purchased from Instruchemie (Hilversum, The Netherlands). The antibodies IOG11, J143 and GOH3 were donated by Dr A.Sonnenberg (Central Laboratory of the Netherlands Red Cross Transfusion Service, Amsterdam, The Netherlands); HP 2/1 and SAM-1 were donated by Dr Carl Figdor (Netherlands Cancer Institute, Amsterdam, The Netherlands). Negative controls included sections incubated without the primary antibody, using PBS/1% bovine serum albumin (BSA) instead. Haematoxylin was used as the counterstain. Endometrium from the appropriate phases of the menstrual cycle served as positive control. Staining intensity was evaluated with light microscopy by two independent observers and scored as no staining, weak staining and positive staining.
Adhesion experiments
Adhesion experiments were performed in 48-well plates. The wells were precoated with either fibronectin (Sanver Tech, Heerhugowaard, The Netherlands), laminin (ICN Biomedical B.V., Zoetermeer, The Netherlands), collagen I (Sanver Tech, Heerhugowaard, The Netherlands), or collagen IV (Sigma Bioscience, St Louis, MO, USA) 10 µg/ml, 200 µl per well. Collagen I was diluted in 0.1% acetic acid and collagen IV was diluted in 0.25% acetic acid. Fibronectin and laminin were diluted with PBS. Before the menstrual endometrium was plated, the wells were rinsed with PBS. Endometrial fragments retained on the 100 µm filter, fragments on the 30 µm filter and the small fragments and single cells <30 µm were plated separately on the four different coatings. CM, 400 µl per well, was added and the cultures were incubated overnight at 37°C. Adhesion was quantified using the MTT assay (see below).
Scanning electron microscopy
For scanning electron microscopy, the fragments retained on the 100 and 30 µm filters were pooled, divided in four aliquots and layered on Thermanox coverslips (ICN) coated with laminin, collagen I, collagen IV or fibronectin. After overnight incubation, the coverslips were rinsed in PBS and fixed in 2.5% glutaraldehyde in phosphate buffer (pH 7.4). Following fixation the samples were dehydrated in a graded series of alcohol, critical point dried, sputtered with gold and examined using a Philips 505 scanning electron microscope (Philips, Eindhoven, The Netherlands).
Blocking experiments
For the blocking experiments, we used: (i) fragments retained on the 30 µm filter, and (ii) small fragments and single cells <30 µm. The tissue fragments and cells were resuspended in CM and preincubated in CM, or in CM containing 0.05 µg/µl of the monoclonal antibody 4B4 against the ß1 subunit of integrins (Coulter Clone, Hialeah, CA, USA), or 0.05 µg/µl of the RGD peptide (GRGDSP, Life Technologies BV, Breda, The Netherlands). Incubations were carried out on a tilted rotating platform at room temperature for 30 min. Next, the tissue was plated in 48-well plates in duplicate on the various coatings and incubated overnight. The tissue incubated with the RGD peptide was only plated on fibronectin. In pilot experiments using proliferative endometrium we titrated the 4B4 antibody (0.025–0.15 µg/µl) and did not observe a further reduction in adhesion when using higher concentrations of 4B4. Additional experiments in which menstrual endometrium was plated on laminin after preincubation with CM, CM containing 0.05 µg/µl 4B4, or CM containing 0.05 µg/µl of the monoclonal antibody GOH3 against the 6ß1 integrin were performed. Following overnight incubation, an MTT assay (see below) was performed to quantify the viable attached cells.
MTT assay
After incubation overnight, CM was discarded and the plates were rinsed once with CM. To each well, 200 µl of CM was added with 30 µl of the tetrazolium salt 3(4,5-dimethylthiazolyl-2)-2,5-diphenyl tetrazolium bromide (MTT) solution (5 mg/ml). MTT is reduced by viable cells to a coloured, water-insoluble formazan salt. After incubating for 4 h at 37°C, the supernatant was discarded and the formazan salt was dissolved in 100 µl dimethylsulphoxide (DMSO). The amount of formazan formed was quantified by measuring the optical density (OD) at 540 nm.
Statistical analysis
The Wilcoxon matched-pairs signed-rank test was used to determine statistically significant differences between the treatment groups. P < 0.05 was considered to be statistically significant.
Results
Immunohistochemistry
A total of 15 samples was collected by seven volunteers. Nine samples were collected during the first day and six samples during the second day of the menstrual cycle. Table I summarizes the results of the histochemical staining with the various monoclonal antibodies against integrins in anterogradely shed menstrual endometrium. We found no differences in expression of integrins between the first and second day of the cycle. Figure 1 is a representative illustration of the staining pattern of the various antibodies used. The integrin 5ß1 was only expressed in stromal cells, whereas the other integrins were all detected in epithelial cells and some in stromal cells.
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Adhesion experiments
Figure 2
summarizes the results of the adhesion studies (n = 18, from nine different volunteers). Adhesion was analysed separately for the different size fractions (fragments >100 µm, fragments 30–100 µm and fragments and single cells < 30 µm) as well as for all fractions combined. Most of the material was found in the fraction with fragments >100 µm and fragments and single cells <30 µm. The fragments with size 30–100 µm were contaminated with desquamated vaginal epithelial cells. Only a few of these vaginal epithelial cells adhered and, therefore, they did not interfere in the adhesion studies. Combined results of all size fractions showed significantly more adhesion to collagen IV and collagen I (P < 0.05) than to fibronectin and laminin. The results are similar for the three different size fractions, as shown in Figure 2.
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Scanning electron microscopy
Two different experiments were performed with menstrual endometrium from two volunteers. When plated on collagen IV (Figure 3A,B
), collagen I (Figure 3C,D) and fibronectin (Figure 3E,F), adherence as well as spreading occurred. When plated on laminin the endometrial fragments adhered but there was hardly any spreading and outgrowth of the cells (Figure 3G,H).
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Blocking experiments
A total of 40 blocking studies were performed, 10 for each coating, using menstrual endometrium from 13 volunteers. The results of the blocking experiments are presented in Figures 4, 5 and 6
. Adhesion of menstrual fragments without preincubation was set at 100%. Preincubation with the 4B4 monoclonal antibody against the integrin ß1 subunit significantly reduced adhesion to 86–82% (P < 0.05) when the fragments were plated on collagen IV, collagen I or fibronectin. Tissue from all size fractions responded similarly to preincubation with this antibody. A significant reduction of adhesion to 51% (P < 0.05) was seen when the incubated fragments were layered on laminin. This was largely due to a reduction to 32% adhesion in the group of smaller fragments < 30 µm (P < 0.05). Fragments of 30–100 µm showed significant reduction of adhesion to 79% (P < 0.05). Additional experiments (n = 10, menstrual endometrium from five volunteers) in which menstrual endometrium was preincubated either with CM, CM with antibody 4B4, or CM with antibody GOH3 and subsequently plated on laminin. Antibody GOH3 against the 6ß1 integrin also significantly reduced adhesion to ~50% in the group of smaller fragments (Figure 5). Preincubation with the GRGDSP peptide (n = 10, menstrual endometrium from five volunteers) reduced adhesion to fibronectin to 84% (P < 0.05) when all size fractions were analysed and the results combined together (Figure 6). When analysed separately, a reduction to 90% (not significant) and 77% (P < 0.05) was found in the groups with larger and smaller fragments respectively.
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Discussion
Studies in our laboratory have demonstrated that anterogradely shed menstrual endometrium is able to adhere to subepithelial layers of amnion and peritoneum (Koks et al., 1999). The findings reported here indicate that adhesion molecules involved in cell–matrix interactions may play an important role. Integrins are transmembrane glycoproteins which act as receptors for ECM proteins. In this study we demonstrate that naturally shed menstrual endometrium expresses at least six integrins. Expression of adhesion molecules, however, does not necessarily imply that these molecules are functionally involved in adhesion. In order to elucidate the mechanisms involved in the adhesion of menstrual endometrium, we performed blocking experiments with two antibodies, 4B4 against the integrin ß1 subunit, and GOH3 against the 6ß1 integrin, and an RGD peptide.
Preferential adherence to collagen IV and I as compared to fibronectin and laminin was observed. These results are in accordance with previous results (Witz et al., 1997). Scanning EM showed striking differences between the adhesion characteristics on the various coatings.
When plated on collagen I, collagen IV or fibronectin the menstrual fragments adhered and spread over the culture surface. In contrast, when plated on laminin, the fragments adhered but showed reduced spreading, suggesting that the various matrix components are differently involved in adhesion. This is corroborated by other authors (Hynes and Lander, 1992; Burrows et al., 1993) who showed that trophoblast cells and neuronal cells remained stationary on laminin and became migratory on fibronectin.
Incubation with 4B4, the antibody to the integrin ß1 subunit, strongly reduced adhesion to laminin. Surprisingly, the reduction in adhesion appeared mostly due to a reduction in adhesion of the fragments and cells <30 µm. A possible explanation for this phenomenon is that the antibody has easy access to the cell surface in a suspension of single cells and small fragments, whereas the antibody cannot interact with the cells in the core of the larger fragments.
Adhesion to the other ECM components was reduced only slightly when the menstrual tissue was preincubated with the 4B4 antibody. Integrins 3ß1 and 6ß1 have been characterized as the principal laminin receptors. Other integrins such as 1ß1 and 2ß1 have been identified as laminin receptors, but are less specific. Since 3ß1 is weakly and 6ß1 strongly expressed in anterogradely shed menstrual endometrium, it is likely that the reduction in adhesion to laminin is due to the inactivation of this 6ß1 laminin receptor. Blocking experiments with GOH3, the antibody against integrin 6ß1 confirmed this.
Adhesion to fibronectin is mediated by the 4ß1, 5ß1 and vß3 integrins. These fibronectin receptors recognize different sequences in fibronectin. 5ß1 and vß3 binding is RGD-dependent, whereas 4ß1 recognizes the alternatively spliced CS-1 segment of fibronectin. The monoclonal antibody against the integrin ß1 subunit does not prevent adhesion to fibronectin mediated by the vß3 integrin, whereas the RGD peptide will block the attachment of 5ß1, and vß3, without interfering with the 4ß1 receptor. In our experiments, both methods of blocking resulted in only minimal reduction of adhesion to fibronectin. Thus neither 4ß1, 5ß1, nor vß3 appear to be important mediators in these particular cell–matrix interactions. Blocking of the collagen receptors 1ß1, 2ß1 and 3ß1 did not reduce adhesion to collagen I and IV, suggesting that these integrins play no significant role in the adhesion of naturally shed menstrual endometrium. Only Witz et al. (1997) and Hopkisson et al. (1996) have attempted to identify integrins involved in endometrial cell adhesion by means of blocking experiments. They used mechanically obtained and enzymatically prepared stromal cells in contrast to whole endometrial fragments and single cells isolated from anterogradely shed menstrual effluent. Witz et al. (1997) incubated stromal cells with echistatin, a disintegrin that blocks binding to the RGD oligopeptide sequence. Their results showed that echistatin decreased endometrial stromal cell adhesion in a dose-dependent manner (Witz et al., 1997). Hopkisson et al. blocked adhesion of stromal cells to ECM by using antibodies to different -integrin subunits (Hopkisson et al., 1996). They did not observe a complete blocking and concluded that more than one integrin may be involved in the binding to individual components of the ECM. Since binding of the menstrual endometrium to the ECM components could not be blocked completely, it is likely that other adhesion mechanisms are involved.
In conclusion, we have shown that naturally shed menstrual endometrium expresses various integrins. In adhesion and blocking experiments we demonstrated that these integrins are involved in adhesion to ECM components. The 6ß1 integrin may play a key role in the adhesion of menstrual tissue to laminin and thus may be of pivotal importance in the very early phases of the development of endometriosis.
Acknowledgments
We thank Liesbeth Bouchet for her technical support and Paul Bomans and Rein van Gool for their expert advice on electron microscopy.
Notes
4 To whom correspondence should be addressed at: Department of Obstetrics and Gynaecology, St Joseph Ziekenhuis, P.O Box 7777, 5500 MB, Veldhoven, The Netherlands
References
Béliard, A., Donnez, J., Nisolle, M. et al. (1997) Localization of laminin,fibronectin, E-cadherin, and integrins in endometrium and endometriosis. Fertil. Steril., 67, 266–272.[Web of Science][Medline]
Bridges, J.E., Prentice, A., Roche, W. et al. (1994) Expression of integrin adhesion molecules in endometrium and endometriosis. Br. J. Obstet. Gynaecol., 101, 696–700.[Web of Science][Medline]
Burrows, T.D, King, A. and Loke, Y.W. (1993) Expression of integrins by human trophoblast and differential adhesion to laminin or fibronectin. Hum. Reprod., 8, 475–484.
Burrows, T.D., King, A., Smith, S.K. et al. (1995) Human trophoblast adhesion to matrix proteins: inhibition and signal transduction. Hum. Reprod., 10, 2489–2500
Creus, M., Balasch, J., Ordi, J. et al. (1998) Integrin expression in normal and out-of-phase endometria. Hum. Reprod., 13, 3460–3468.
Gehlsen, K.R., Argraves, W.S., Pierschbacher, M.D. et al. (1988) Inhibition of in vitro tumor cell invasion by Arg-Gly-Asp-containing synthetic peptides. J. Cell Biol., 106, 925–930.
Groothuis, P.G., Koks, C.A.M., de Goeij, A.F.P.M. et al. (1998) Adhesion of human endometrium to the epithelial lining and extracellular matrix of amnion in vitro: An electron microscopic study. Hum. Reprod., 13, 2275–2281.
Hii, L.L.P. and Rogers, P.A.W. (1998) Endometrial vascular and glandular expression of integrin vß3 in women with and without endometriosis. Hum. Reprod., 13, 1030–1035.
Hopkisson, J.F., Kennedy, S.H., Barlow, D.H. et al. (1996) The expression and function of integrins on endometrial stromal cells. [Abstr. no. O61] Hum. Reprod., 11 (Abstr. Book 1), 28.
Hynes, R.O. and Lander, A.D. (1992) Contact and adhesive specificities in the associations, migrations, and targeting of cells and axons. Cell, 68, 303–322.[Web of Science][Medline]
Koks, C.A.M., Dunselman G.A.J., de Goeij A.F.P.M. et al. (1997) Evaluation of a menstrual cup to collect shed endometrium for in vitro studies. Fertil. Steril., 68, 560–564.[Web of Science][Medline]
Koks, C.A.M., Groothuis, P.G., de Goeij, A.F.P.M. et al. (1999) Adhesion of shed menstrual tissue in an in-vitro model using amnion and peritoneum: a light microscopic and electron microscopic study. Hum Reprod., 14, 816–822.
Lessey, B.A. (1998) Endometrial integrins and the establishment of uterine receptivity. Hum. Reprod., 13 (Suppl. 3), 247–258.
Lessey, B.A., Castelbaum, A.J., Sawin, S.W. et al. (1994) Aberrant integrin expression in the endometrium of women with endometriosis. J. Clin. Endocrinol. Metab., 79, 643–649.[Abstract]
Lessey, B.A., Ilesanmi, A.O., Lessey, M.A. et al. (1996) Luminal and glandular endometrial epithelium express integrins differentially throughout the menstrual cycle: implications for implantation, contraception, and infertility. Am. J. Reprod. Immunol., 35, 195–204.
Ota, H. and Tanaka, T. (1997) Integrin adhesion molecules in the endometrial glandular epithelium in patients with endometriosis or adenomyosis. J. Obstet. Gynaecol. Res., 23, 485–491.[Medline]
Rai, V., Hopkisson, J., Kennedy, S. et al. (1996) Integrins alpha 3 and alpha 6 are differentially expressed in endometrium and endometriosis. J. Pathol., 180, 181–187.[Web of Science][Medline]
Regidor, P.A., Vogel, C., Regidor, M. et al. (1998) Expression pattern of integrin adhesion molecules in endometriosis and human endometrium. Hum. Reprod., Update, 4, 710–718.
Ruoslahti, E. and Pierschbacher, M.D. (1987) New perspectives in cell adhesion: RGD and integrins. Science, 238, 491–496.
Sampson, J.A. (1940) The development of the implantation theory for the origin of peritoneal endometriosis. Am. J. Obstet. Gynecol., 40, 549–57.
Shiokawa, S., Yoshimura, Y., Nagamatsu, S. et al. (1998) Functional role of focal adhesion kinase in the process of implantation. Mol. Hum. Reprod., 4, 907–914.
Tabibzadeh, S. (1992) Patterns of expression of integrin molecules in human endometrium throughout the menstrual cycle. Hum. Reprod., 7, 876–882.
Van der Linden, P.J.Q., de Goeij, A.F.P.M., Dunselman, G.A.J. et al. (1994) Expression of integrins and E-cadherin in cells from menstrual effluent, endometrium, peritoneal fluid, peritoneum and endometriosis. Fertil. Steril., 61, 85–90.[Web of Science][Medline]
Van der Linden, P.J.Q., de Goeij, A.F.P.M., Dunselman, G.A.J. et al. (1995) Expression of cadherins and integrins throughout the menstrual cycle. Fertil. Steril., 63, 1210–1216.[Web of Science][Medline]
Van der Linden, P.J.Q., de Goeij, A.F.P.M., Dunselman, G.A.J. et al. (1996) Endometrial cell adhesion in an in vitro model using intact amniotic membranes. Fertil. Steril., 65, 76–80.[Web of Science][Medline]
Van der Linden, P.J.Q., de Goeij, A.F.P.M., Dunselman, G.A.J. et al. (1998) Amniotic membranes as an in vitro model for endometrium extracellular matrix interactions. Gynecol. Obstet. Invest., 57, 7–11.
Witz, C.A., Doucet, R.V., Honore, G.M. et al. (1997) Preferential endometrial stromal cell adhesion to collagen IV and collagen I is inhibited by echistatin. [Abstr. no. O-026.] Fertil. Steril. (Suppl.), S14.
Witz, C.A., Monotoya-Rodriguez, I.A. and Schenken, R.S. (1999) Whole explants of peritoneum and endometrium: a novel model of the early endometriosis lesion. Fertil. Steril., 71, 56–60.[Web of Science][Medline]
Submitted on April 26, 1999; accepted on October 28, 1999.
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