Ultrastructural cytochemical characterization of collagen-associated proteoglycans in the endometrium of mice

Distribution of extracellular matrix molecules in human uterine tubes during the menstrual cycle: a histological and immunohistochemical analysis

The uterine tube (UT) is an important and complex organ of the women's reproductive system. In general, the anatomy and basic histology of this organ are well-known. However, the composition and function of the extracellular matrix (ECM) of the UT is still poorly understood. The ECM is a complex supramolecular material produced by cells which is commonly restricted to the basement membrane and interstitial spaces. ECM molecules play not only a structural role, they are also important for cell growth, survival and differentiation in all tissues. In this context, the aim of this study was to evaluate the deposition and distribution of type I and III collagens and proteoglycans (decorin, biglycan, fibromodulin and versican) in human UT during the follicular and luteal phases by using histochemical and immunohistochemical techniques. Our results showed a broad synthesis of collagens (I and III) in the stroma of the UT. The analysis by regions showed, in the mucosa, a specific distribution of versican and fibromodulin in the epithelial surface, whereas decorin and fibromodulin were observed in the lamina propria. Versican and decorin were found in the stroma of the muscular layer, whereas all studied proteoglycans were identified in the serosa. Curiously, biglycan was restricted to the wall of the blood vessels of the serosa and muscular layers. Furthermore, there was an immunoreaction for collagens, decorin, versican and fibromodulin in the UT peripheral nerves. The differential distribution of these ECM molecules in the different layers of the UT could be related to specific structural and/or biomechanical functions needed for the oviductal transport, successful fertilization and early embryogenesis. However, further molecular studies under physiological and pathological conditions are still needed to elucidate the specific role of each molecule in the human UT.

Concentration of sulfated glycosaminoglycans in the mammary tissue of female rats with the aging and about hormonal influence

It was to evaluate the concentration of sulfate glycosaminoglycans (GAG) in mammary tissue of the young and adult female rats and ovariectomized females rats after hormonal stimulation. For this purpose, 60 female rats were divided into six groups with 10 animals/each: nonovariectomized groups: G1 (5 months), and G2 (15 months) and ovariectomized groups: OG (vehicle); EG: (estradiol, 7 days of treatment), PG (progesterone acetate, 23 days of treatment) and EPG: (estradiol (7 days of treatment) and next progesterone acetate (23 days of treatment). Twenty-four hours after the last treatment, all animals were euthanized, the mammary tissue removed, processed for biochemical evaluation and quantification of the GAG. The comparison between groups showed that the concentration dermatan sulfate (DS) G1 was lower compared to G2, OG, EG (p < .05) and G2 was lower compared to OG (p < .05), and OG was higher compared to EG, GP, EPG (p < .05); and heparan sulfate (HS) G1 was higher compared to G2 (p < .05), and G2 was higher compared to OG, EP, PG and EPG (p < .05). These changes in the extracellular matrix might explain, at least in part, hormonal influence about sulfated glycosaminoglycans in response to physiological state/age, and in response to hormonal treatment in the mammary tissues.

The absence of the embryo in the pseudopregnant uterus alters the deposition of some ECM molecules during decidualization in mice

The embryo-implantation promotes deep changes in the uterus resulting in the formation of a new structure at the maternal-fetal interface, the decidua. Decidualization can also be induced in pseudopregnant rodents resulting in a structure called deciduoma that is morphologically and functionally similar to the decidua. Previous studies from our and other laboratories demonstrate that in rodents, decidualization of the endometrium requires remarkable remodeling of the endometrial extracellular matrix (ECM) that is mainly coordinated by estradiol and progesterone. The influence of the embryo in this process, however, has not yet been investigated. To enlarge the knowledge on this subject, the present study investigates the behavior of a set of ECM molecules, in the absence of paracrine cues originated from the embryo. For that deciduoma was induced in pseudopregnant Swiss mice, and the distribution of collagen types I, III, IV, V and the proteoglycans decorin and biglycan was investigated by immunolabeling from the fifth to the eighth day of pseudopregnancy. It was observed the deposition of collagen types III and IV as well as decorin and biglycan was similar to that previously described by our group in the decidua. However, in the absence of the embryo, some differences occur in the distribution of collagen types I and V, suggesting that beside the major role of ovarian hormones on the endometrial ECM remodeling, molecular signals originated from the conceptus may influence this process.

Glycosaminoglycan distribution in the rat uterine cervix during the estrous cycle

OBJECTIVE

To analyze the amount of glycosaminoglycans in the uterine cervix during each phase of the rat estrous cycle.

DESIGN

Based on vaginal smears, forty female, regularly cycling rats were divided into four groups (n = 10 for each group): GI - proestrous, GII - estrous, GIII - metaestrous and GIV - diestrous. Animals were sacrificed at each phase of the cycle, and the cervix was immediately removed and submitted to biochemical extraction and determination of sulfated glycosaminoglycans and hyaluronic acid. The results were analyzed by ANOVA followed by the Bonferroni post-hoc test.

RESULTS

The uterine cervix had the highest amount of total sulfated glycosaminoglycans and dermatan sulfate during the estrous phase (8.90 +/- 0.55 mg/g of cetonic extract, p<0.001; and 8.86 +/- 0.57 mg/g of cetonic extract, p<0.001). In addition, there was more heparan sulfate at the cervix during the proestrous phase (0.185 +/- 0.03 mg/g of cetonic extract) than during any other phase (p<0.001). There were no significant changes in the concentration of hyaluronic acid in the uterine cervix during the estrous cycle.

CONCLUSION

Our data suggest that the amount of total sulfated glycosaminoglycans may be influenced by hormonal fluctuations related to the estrous cycle, with dermatan sulfate and heparan sulfate being the glycosaminoglycans most sensitive to hormonal change.

Collagen fibril organization in the pregnant endometrium of decorin-deficient mice

In the pregnant mouse endometrium, collagen fibrillogenesis is characterized by the presence of very thick collagen fibrils which are topographically located exclusively within the decidualized stroma. This dynamic biological process is in part regulated by the small leucine-rich proteoglycans decorin and biglycan. In the present study we utilized wild-type (Dcn(+/+)) and decorin-deficient (Dcn(-/-)) time-pregnant mice to investigate the evolution of non-decidualized and decidualized collagen matrix in the uterine wall of these animals. Ultrastructural and morphometric analyses revealed that the organization of collagen fibrils in the pregnant endometrium of both non-decidualized and decidualized stroma showed a great variability of shape and size, regardless of the genotype. However, the decidualized endometrium from Dcn(-/-) mice contained fibrils with larger diameter and more irregular contours as compared to the wild-type littermates. In the Dcn(-/-) animals, the proportion of thin (10-50 nm) fibrils was also higher as compared to Dcn(+/+) animals. On day 7 of pregnancy, biglycan was similarly localized in the decidualized endometrium in both genotypes. Lumican immunostaining was intense both in decidualized and non-decidualized stroma from Dcn(-/-) animals. The present results support previous findings suggesting that decorin participates in uterine collagen fibrillogenesis. In addition, we suggest that the absence of decorin disturbs the process of lateral assembly of thin fibrils, resulting in very thick collagen fibrils with irregular profiles. Our data further suggest that decorin, biglycan and lumican might play an interactive role in collagen fibrillogenesis in the mouse endometrium, a process modulated according to the stage of pregnancy.

Decidual cells produce a heparin-binding prolactin family cytokine with putative intrauterine regulatory actions

Pregnancy in mice and rats is associated with the production of a large family of hormones/cytokines related to prolactin (PRL). The hormones/cytokines are hypothesized to coordinate maternal and fetal adaptations to pregnancy. In this study, PRL-like protein-J (PLP-J, also known as PRL family 3, subfamily c, member 1 (Prl3c1)) is shown to be a product of the uterine decidua and a regulator of postimplantation intrauterine events. PLP-J-specific antibodies and a series of recombinant PLP-J proteins were generated and used to investigate PLP-J expression and as ligands for investigating biological targets. Decidual PLP-J migrates as a 29-kDa protein and localizes to a band of decidual cells surrounding the trophoblast cell layer on gestation day 8.5. PLP-J ligands specifically bound in situ to the surrounding uterine stromal cells and vasculature within the decidua of gestation day 8.5 implantation sites. We then investigated the in vitro actions of PLP-J on uterine stromal cells and endothelial cells. PLP-J specifically interacted with both cell populations. PLP-J promoted uterine stromal cell proliferation and inhibited endothelial cell proliferation. We determined that PLP-J does not interact with PRL receptors. Instead, PLP-J interacts with heparin-containing molecules, including syndecan-1, which is expressed in gestation day 8.5 pregnant uteri, as well as in uterine stromal cells and endothelial cells. The restricted expression of PLP-J and its specific interactions with uterine stromal cells and endothelial cells suggests that it acts locally and regulates decidual cell development and the endometrial vasculature.

Distribution of collagen types I, III, and V in pregnant mouse endometrium

Decidualization in mice comprises a deep remodeling of extracellular matrix (ECM) components of the endometrium. In a previous biochemical study we showed that collagen types I and III are present in both pregnant and nonpregnant mouse endometrium, whereas collagen type V is expressed exclusively after the onset of decidualization. The distribution of collagen types in the pregnant mouse endometrium and possible changes of these molecular types in the different regions of the decidua is, however, not known. Using immunofluorescence and confocal microscopy we showed the presence of collagen types I, III, and V in the endometrial stroma of implantation and interimplantation sites from days 5 to 8 of pregnancy in the mouse. Collagen type III was chiefly expressed in the implantation sites and was the only collagen type to be present in the materno-fetal interface on the day of the embryo implantation. However, collagen type I was the predominant collagen in the interimplantation sites. Collagen type V was weakly expressed in the nondecidualized stroma during all periods but was expressed in larger amounts in the decidualized areas on day 7 of pregnancy, simultaneously with the accumulation of thick collagen fibrils in the same region. The highest immunofluorescence labeling for the three types of collagen was observed on day 7 when the antimesometrial decidual tissue achieved its greatest development. These data support previous studies that showed an intense ECM remodeling of the mouse endometrial stroma during the beginning of pregnancy. This outstanding remodeling may be important to stabilize placental anchorage.

Implication of ADAM-8, -9, -10, -12, -15, -17, and ADAMTS-1 in implantational remodeling of a mouse uterus

In the present study, whether the ADAM-8, -9, -10, -12, -15, -17, and ADAMTS-1 proteins might play a role in mouse uterus during periimplantation period was investigated. Immunoblotting analyses demonstrated that all ADAM proteins consistently appeared throughout days 1 to 8 of pregnancy but with a variation depending on the species of ADAM gene, the progression of pregnancy, and the site of the uterus. Immunohistochemical analyses indicated that ADAM proteins were localized in the luminal or glandular epithelial layers with a varying intensity depending on the species of ADAM and the progression of pregnancy. Particularly ADAM-8, -12, and -15, were predominantly located in the implantation site of the uterine tissues, whereas little or no protein was localized in the interimplantation site. Based upon these observations, it is suggested that the ADAMs might play an important role in the remodeling of the mouse uterus during the periimplantation period.

Arrangement and fine structure of collagen fibrils in the decidualized mouse endometrium

The adaptations of the mouse uterus to pregnancy include extensive modifications of the cells and extracellular matrix of the endometrial connective tissue that surround the embryos. Around each implanted embryo this tissue redifferentiates into a transient structure called decidua, which is formed by polygonal cells joined by intercellular junctions. In the mouse, thick collagen fibrils with irregular profile appear in decidualized areas of the endometrium but not in the nondecidualized stroma and interimplantation sites. The fine organization of these thick fibrils has not yet been established. This work was addressed to understand the arrangement and fine structure of collagen fibrils of the decidua of pregnant mice during the periimplantation stage. Major modifications occurred in collagen fibrils that surrounded decidual cells: (1) the fibrils, which were arranged in parallel bundles in nonpregnant animals, became organized as baskets around decidual cells; (2) very thick collagen fibrils with very irregular profiles appeared around decidual cells. Analysis of replicas and serial sections suggests that the thick collagen fibrils form by the lateral aggregation of thinner fibrils to a central fibril resulting in very irregular profile observed in cross sections of thick fibrils. The sum of modifications of the collagen fibrils seem to represent an adaptation of the endometrium to better support the decidual cells while they hold the embryos during the beginning of their development. The deposition of thick collagen fibrils in the decidua may contribute to form a barrier that impedes leukocyte migration within the decidua, preventing immunological rejection of genetically dissimilar embryonic tissues.

Aquaporin-1 increases in the rat myometrium during early pregnancy

Immunofluorescence and immunogold techniques were used to determine the presence and distribution of aquaporin-1 (AQP1) within the rat uterus. Uterine tissue from non-pregnant (proestrus) as well as pregnant (days 1, 3, 6 and 7) rats were used. It was found that this water channel was present in the myometrium of the pregnant rat uterus with the intensity of AQP1 immunoreactivity increasing from day 1 to day 6 of pregnancy. In particular, an increase was also observed in mesometrial as compared to antimesometrial myometrium. Immunolocalization at the electron microscope level indicated that AQP1 was localized to the plasma membrane of smooth muscle cells found within the inner circular layer. It is suggested that AQP1 plays a role in stromal oedema, uterine closure and orientation of the blastocyst.

Distribution of versican and hyaluronan in the mouse uterus during decidualization

Preparation for embryo implantation requires extensive adaptation of the uterine microenvironment. This process consists of cell proliferation and cell differentiation resulting in the transformation of endometrial fibroblasts into a new type of cell called decidual cell. In the present study, we followed the space-time distribution of versican and hyaluronan (HA) in different tissues of the uterus before and after embryo implantation. Fragments of mouse uteri obtained on the fourth, fifth, sixth and seventh days of pregnancy were fixed in Methacarn, embedded in Paraplast and cut into 5-microm thick sections. HA was detected using a biotinylated fragment of the proteoglycan aggrecan, which binds to this glycosaminoglycan with high affinity and specificity. Versican was detected by a polyclonal antibody. Both reactions were developed by peroxidase methods. Before embryo implantation, both HA and versican were present in the endometrial stroma. However, after embryo implantation, HA disappeared from the decidual region immediately surrounding the implantation chamber, whereas versican accumulated in the same region. The differences observed in the expression of HA and versican suggest that both molecules may participate in the process of endometrial decidualization and/or embryo implantation.

Copper retention, calcium release and ultrastructural evidence indicate specific Cuprolinic Blue uptake and peculiar modifications in mineralizing aortic valves

Previously, reactions with copper phthalocyanines at 0.05 M critical electrolyte concentration were found to cause demineralization in calcifying porcine aortic valves after subdermal implantation in rat, as well as simultaneous visualization of peculiar phthalocyanine-positive layers around cells and cell-derived matrix vesicles. In the present investigation, an appraisal was made of the mechanism and specificity of reactions with Cuprolinic Blue by comparing quantitatively calcium release and copper retention by calcified aortic valves reacted with this phthalocyanine under different critical electrolyte concentration conditions, and the corresponding ultrastructural patterns. It was found that (i) decalcifying properties are inversely proportional to salt molarity; (ii) reactivity to Cuprolinic Blue is critical electrolyte concentration-dependent, since the greatest copper retention occurred in 0.05 M critical electrolyte concentration Cuprolinic Blue-reacted samples, the only ones that also exhibited phthalocyanine-positive layers; (iii) the appearance of phthalocyanine-positive layers depends on Cuprolinic Blue uptake, revealing pericellular clustering of calcium-binding, anionic molecules; and (iv) minor Cuprolinic Blue uptake occurs by residual proteoglycans which still remain in the extracellular matrix after 6-week-long subdermal implantation. The present results indicate that this method is appropriate for the study of mineralized tissues and illustrate peculiar tissue modifications occurring at least in the experimental conditions used here.