| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Departments of Cell & Developmental Biology,4 Pediatrics,5 and Pharmacology,6 Vanderbilt University Medical Center, Nashville, Tennessee 37232
ABSTRACT
Reduced litter sizes in mice missing pentraxin 3 (Ptx3) have been attributed to fertilization failure. However, our global gene expression studies showed high uterine Ptx3 expression at the implantation site in mice, suggesting its role in blastocyst implantation. We initiated molecular and genetic studies in mice to explore the importance of uterine Ptx3 in this process. We found that Ptx3 is expressed in a unique and transient fashion at implantation sites. With the initiation of implantation on midnight of Day 4 of pregnancy, Ptx3 is expressed exclusively in stromal cells at the site of blastocysts. On Day 5, its expression is more intense in decidualizing stromal cells, but it disappears on Day 6. The expression again becomes evident in the deciduum on Day 7, followed by a more robust expression on Day 8, particularly at the antimesometrial pole. From Day 9, with the initiation of placentation, Ptx3 expression becomes undetectable. These results suggest a role for PTX3 in implantation and decidualization. Indeed, deletion of Ptx3 results in both compromised implantation and decidualization. Interleukin 1B (IL1B), a known inducer of Ptx3, is also transiently expressed in stromal cells at the implantation site, suggesting that IL1B is an inducer of uterine Ptx3 expression. In fact, uterine Ptx3 expression follows that of Il1b induced by lipopolysaccharide treatment on Day 7 of pregnancy. Collectively, these findings provide evidence for an important role for PTX3 in implantation and decidualization. This study has clinical implications, since PTX3 is expressed in the receptive endometrium, and trophoblast cells influence decidual Ptx3 expression in humans.
embryo, implantation, pregnancy, uterus
A reciprocal interaction between the blastocyst and uterus is absolutely required for implantation [1]. The major events for the success of this process involve epithelial-epithelial interactions between the blastocyst trophectoderm and the uterine luminal epithelium, regulated invasion of the trophoblast through the luminal epithelium and the underlying basement membrane, transformation of stromal cells into decidual cells surrounding the implanting blastocyst, and protection of the semiallogenic embryo from the mother's immunologic responses. Unlike other tissues, the uterus is considered an immunologically privileged site, because the semiallogenic embryo, despite its genetic incompatibility, is not rejected by maternal immunologic surveillance [2, 3]. The mechanism by which the semiallogenic embryo is protected during pregnancy from the maternal immunologic responses is not fully understood.
Global gene expression studies in mice and humans have shown that numerous immunologically relevant genes are downregulated at the site of blastocyst implantation, with the exception of a few genes, including pentraxin 3 (Ptx3) and decay-accelerating factor 1 (Daf1) [4, 5]. The upregulation of these genes implies their potential role in protecting the embryo from maternal immunologic and/or other noxious stimuli. Although Daf1-deficient female mice are fertile [6], most Ptx3-null females show pregnancy failure, attributed primarily to fertilization defects [7, 8]. However, a role for PTX3 in uterine biology and implantation remains unknown and is therefore the subject of the present investigation.
PTX3, also known as tumor necrosis factor (TNF)-stimulated gene 14 (TSG14), is a member of the pentraxin superfamily, a family characterized by a cyclic multimeric structure and subdivided into two classes: short and long pentraxins [9]. Pentraxins are acute-phase molecules whose expression increases in response to inflammatory stimuli. They are composed of monomers that usually assemble into pentameric, noncovalently associated structures [10–12]. Pentraxin 3 is a long pentraxin, originally cloned as an interleukin 1 (IL1)-inducible and tumor necrosis factor 
(TNF)-inducible gene in endothelial cells and fibroblasts, respectively [13, 14]. Interestingly, PTX3 does not bind to classical pentraxin ligands, such as phosphoethanolamine, phosphocholine, or fibronectin. Instead, PTX3 binds with high affinity to the globular domain of complement component C1q [15, 16]. In vitro studies have shown that PTX3 recognizes membrane moieties, including galactomannan, OmpA (a bacterial moiety outer membrane protein A), histones, and matrix protein TSG6 (reviewed in [17, 18]). There is also evidence that the N-terminal of PTX3 binds to fibroblast growth factor 2 (FGF2) to restrain FGF2's proliferative and proangiogenic activity [19, 20]. PTX3 is also known to play roles in immunity and apoptosis [9, 17, 18, 21].
Targeted deletion of Ptx3 results in reduced fertility, due to an early loss of cumulus investment, leading to fertilization failure [7, 8]. It is thought that PTX3 binding to TSG6 stimulates the assembly of a hyaluronic acid-rich extracellular matrix, which is essential for cumulus expansion, and therefore this event fails with deletion of Ptx3 [8]. In this investigation, we studied the role of PTX3 in implantation and decidualization. We observed that not only is Ptx3 uniquely expressed in the mouse uterus during the periimplantation period in a temporal and cell-specific manner, but implantation and decidualization are also compromised in mice deficient for Ptx3. These results provide molecular and genetic evidence that PTX3 is an important member of the signaling network operative during implantation and decidualization. Recent studies showing its upregulation in receptive human endometria and its induction in decidua by trophoblast cells also suggest an important role for PTX3 in human implantation [22, 23].
Disruption of the Ptx3 gene was originally achieved in AB2.2 embryonic stem cells by homologous recombination as described [8]. Breeding pairs of Ptx3-null mice on a C57/129 mixed background were kindly provided by Martin M. Matzuk (Baylor College of Medicine, Houston, TX) and are being maintained on the same background in our animal care facility. Genotyping is routinely performed by PCR analysis of genomic DNA. CD1 mice used for expression studies were purchased from Charles River Laboratory (Raleigh, NC). All mice were housed in the animal care facility at Vanderbilt University Medical Center according to the National Institutes of Health and institutional guidelines for laboratory animals.
Experimentally Induced Deciduoma and Delayed Implantation
Adult virgin females (20–25 g) were mated with fertile males of the same strain to induce pregnancy (Day 1 = vaginal plug). Implantation sites on Day 5 of pregnancy were visualized by an intravenous injection (0.1 ml per mouse) of Chicago blue dye solution (1% in saline) as described previously [24] and were collected separately from interimplantation sites. Implantation sites collected on Days 7 and 8 of pregnancy are easily visualized, requiring no blue dye injection, and were also collected separately from interimplantation sites. Conditions of delayed implantation were induced by ovariectomizing females on the morning (0900–0930 h) of Day 4 and were maintained with daily subcutaneous injections of progesterone (P4, 2 mg per mouse) from Days 5 to 7. To initiate implantation with the activation of dormant blastocysts, P4-primed mice were injected with estradiol-17ß (E2, 25 ng per mouse) on Day 7 of pregnancy and were killed 12 and 24 h later to examine implantation status by the blue dye method. Wild-type and null females were mated with fertile males, and uteri were collected on Days 1 and 4 of pregnancy to examine expression of estrogen and progesterone target genes, respectively. For experimentally induced decidualization, wild-type or Ptx3-null littermate females were mated with vasectomized wild-type males to induce pseudopregnancy. Sesame oil (20 µl) was infused intraluminally in one uterine horn on Day 4 of pseudopregnancy, and the noninfused contralateral horn served as a control. Wild-type mice were killed on Days 5, 6, and 8 of pseudopregnancy to examine Ptx3 expression. Control and oil-infused uteri from wild-type and null mice were weighed on Day 8 to assess the extent of decidualization.
Pseudopregnant recipients were generated by mating wild-type or Ptx3–/– females with vasectomized wild-type males. Wild-type Day 4 blastocysts were transferred into Day 3 or 4 uteri of wild-type or Ptx3–/– pseudopregnant recipients. No differences were observed whether embryos were transferred on Day 3 or 4 of pseudopregnancy, so results were pooled. Mice were examined for implantation sites 24 h (Day 5) or 96 h (Day 8) later by the blue dye method. All female mice used were 2–5 mo of age. Uteri devoid of implantation sites were flushed with saline to recover unimplanted blastocysts.
Adult virgin female mice (20–25 g) were mated with fertile males of the same strain to induce pregnancy. On Day 7 of pregnancy (0900 h), mice were intraperitoneally injected with lipopolysaccharide (LPS; 100 µg/0.1 ml saline; Sigma, St. Louis, MO). Liver and uterine tissues were collected at 0, 1, 2, and 6 h after injection for isolation of RNA.
For in situ hybridization, sense and antisense 35S-labeled cRNA probes for Ptx3, Il1b, Ltf, Areg, and Hoxa10 were generated from cDNAs using appropriate polymerases. For Northern hybridization, antisense 32P-labeled cRNA probes for Ptx3, Il1b, and Rpl7 (a housekeeping gene) were generated. Probes had specific activities of 
2 x 109 dpm/µg.
RNA Preparation and Northern Blot Hybridization
Total RNA was extracted from three independent tissue samples using Trizol reagent (Invitrogen, Carlsbad, CA). RNA (6 µg) was denatured, separated by formaldehyde-agarose gel electrophoresis, and transferred onto nylon membranes. Cross-linked blots were prehybridized, hybridized, and washed as previously described [25]. Hybrids were detected by autoradiography.
In situ hybridization was performed as previously described by us [25]. In brief, sections were prehybridized and hybridized at 45°C for 4 h in 50% formamide hybridization buffer containing 35S-labeled antisense or sense cRNA probes. RNase A-resistant hybrids were detected by autoradiography. Sections were poststained with hematoxylin-eosin. Sections hybridized with sense probes did not exhibit any positive signals and served as negative controls. Experiments were repeated at least two to three times using independent samples.
Ptx3 Is Expressed at Higher Levels at the Implantation Site in a Spatiotemporal Manner
Our gene profiling studies in mice showed that while most immunologically related genes are downregulated at the site of implantation, Ptx3 is one of the few genes that is upregulated instead [5]. Later, it was found that Ptx3 expression is also upregulated in human endometrium during the receptive phase [4]. These results suggest that PTX3 is important for uterine function relevant to implantation. To first confirm our microarray results [5], we compared the levels of Ptx3 mRNA between implantation and interimplantation sites on Days 5 and 8 of pregnancy in mice by Northern hybridization. As noted in Figure 1A, the levels of Ptx3 mRNA are considerably higher at implantation sites compared with those at interimplantation sites on Days 5 and 8, affirming our microarray results.
|
The uterus is comprised of heterogeneous cell types that undergo dramatic changes during early pregnancy [26]. Thus, we next examined the cell-specific and temporal expression of Ptx3 in the periimplantation uterus using in situ hybridization. We found an interesting expression pattern. Ptx3 is expressed at low to undetectable levels in the uterus on Days 1 and 4 of pregnancy (Fig. 1B). The Day 1 uterus is predominantly under the influence of preovulatory estrogen, whereas the Day 4 uterine milieu is dominated by rising progesterone (P4) levels from the newly formed corpora lutea [26]. These results suggest that ovarian steroids estrogen and P4 play a small, if any, role in regulating uterine Ptx3 expression. In contrast, the expression pattern of Ptx3 dramatically changed with the onset of implantation. The initiation of blastocyst attachment coincides with an increased endometrial vascular permeability and increased stromal cell proliferation at the site of blastocyst attachment. We found that Ptx3 is first expressed in stromal cells surrounding the blastocyst with the initiation of its attachment with the luminal epithelium on midnight of Day 4 of pregnancy. On Day 5, stromal cell proliferation is more intense at this site, and so is the expression of Ptx3 (Fig. 1B). The proliferating and differentiating stromal cells surrounding the implanting blastocyst begin to form the primary decidual zone (PDZ) late on Day 5 of pregnancy. The PDZ is avascular and densely packed with decidual cells. By Day 6, the PDZ is well established, and a secondary decidual zone (SDZ) is formed around the PDZ. At this time, cell proliferation ceases in the PDZ but still continues in the SDZ. On this day, Ptx3 expression becomes very low to undetectable. Surprisingly, its expression reappears on Day 7 of pregnancy at the border between the PDZ and SDZ, and it becomes more intense on Day 8. With the beginning of placentation and decidual regression on Days 9 and 10, Ptx3 expression disappears (Fig. 1B and data not shown).
Ptx3-null Mice Show Compromised Implantation and Decidualization
The unique expression pattern of Ptx3 in the peri-implantation uterus led us to ask whether uterine PTX3 plays a role during early pregnancy. Targeted deletion of Ptx3 in mice results in severely reduced fertility, primarily resulting from failure of oocyte fertilization associated with defective cumulus cell expansion [7, 8]. Although pregnancy can occur in Ptx3-null females, litter sizes are drastically reduced [8]. These observations, together with the unique uterine expression pattern of Ptx3, led us to explore whether the implantation process is also defective in Ptx3-null females. Since these null females have severely compromised fertilization [7, 8], we employed reciprocal blastocyst transfer experiments to examine implantation status in these mice. Day 4 wild-type blastocysts were transferred into the uteri of Day 4 pseudopregnant wild-type or null recipients. Although 53% of the transferred blastocysts implanted into all five wild-type recipient uteri, only a small percentage (17%) of transferred blastocysts showed signs of implantation in just four of eight Ptx3-null uteri. Recovery of blastocysts from null recipients confirmed efficacy of transfer. When examined on Day 8, again, only three of seven Ptx3-null mice showed signs of implantation, and the number of implantation sites was low (23%; Table 1).
|
Estrogen- and Progesterone-Regulated Genes are Normally Expressed in the Ptx3 Uterus Prior to Implantation
The results of blastocyst transfer experiments suggested that uteri missing PTX3 are not fully competent for implantation. One cause of this compromised implantation could be due to inadequate preparation of the uterus to the receptive state in response to ovarian estrogen and P4. To ensure that Ptx3-null females attained appropriate uterine receptivity, we examined estrogen- and P4-responsive genes that are differentially regulated on Day 4 (the day of the receptive phase). Although the estrogen-responsive gene lactoferrin (Ltf) is highly expressed in the uterine epithelium on Day 1 of pregnancy under the preovulatory estrogen surge, this gene is dramatically downregulated when the uterus undergoes P4 dominance on Day 4 [26]. We found that although Ltf is highly expressed in the uterine epithelia of both wild-type and Ptx3–/– mice on Day 1 (Fig. 2A), it is dramatically downregulated on Day 4 of pregnancy in both null and wild-type mice (Fig. 2B). Hoxa10 and amphiregulin (Areg) are P4-regulated genes in mice and are expressed in a cell-specific manner in the receptive uterus on Day 4 of pregnancy [27, 28]. We found that the expression pattern of these genes is comparable between wild-type and null uteri on Day 4 (Fig. 2B), suggesting that the loss of Ptx3 does not interfere with uterine receptivity achieved under coordinated P4 and estrogen signaling.
|
Decidualization is Compromised in the Absence of PTX3
Since Ptx3 expression is biphasic, first showing its expression in stromal cells with the onset of blastocyst attachment and then in decidual cells following implantation, we sought to examine whether PTX3 participates in decidualization and whether embryonic signals are absolutely required for decidual Ptx3 expression. We used the model of experimentally induced decidualization to address these questions. In the absence of fertilized embryos in pseudopregnant mice, the steroid hormonal milieu within the uterus is similar to normal pregnancy, and nonspecific stimuli, such as mechanical trauma or intraluminal oil infusion, evoke many aspects of decidual cell reactions similar to those induced by living blastocysts [26]. On Day 4 of pseudopregnancy, 20 µl sesame oil was injected intraluminally into one uterine horn of each pseudopregnant wild-type mouse; the contralateral horn served as a control. Mice were sacrificed on Days 5, 6, and 8, and in situ hybridization was performed to localize Ptx3 expression in uterine sections (Fig. 3A). We found that the Ptx3 expression pattern in oil-induced decidualizing stromal cells closely resembles that observed during normal pregnancy, suggesting that signals arising from the implanting blastocysts are not an absolute requirement for decidual Ptx3 induction.
|
Since Ptx3 is expressed in the deciduoma induced by intraluminal oil infusion, we next investigated this event in the absence of PTX3. We found that intraluminal oil infusion on Day 4 of pseudopregnancy in Ptx3-null mice resulted in significantly diminished decidual responses compared with those observed in oil-infused wild-type uteri (Fig. 3, B and C). More specifically, while all of the wild-type mice showed typical decidual responses averaging 8-fold change in uterine weight between control and oil-infused horns, three of seven null mice showed no decidual responses. The highest fold change in weight between control and oil-infused uterine horns observed in one Ptx3–/– female was 4.3; a photograph of this uterus is shown (Fig. 3C). These results suggest that the ability of the uterine stroma to respond to decidualization is compromised in the absence of Ptx3, implying a role for PTX3 in this event as well.
Il1b Induction Precedes Ptx3 Expression in the Pregnant Mouse Uterus
Unlike classic pentraxins present in the liver, PTX3 is produced by macrophages and a variety of tissues upon exposure to inflammatory stimuli, one being IL1B [9]. LPS is a known inducer of IL1B, and we have previously shown that an injection of LPS induces Il1b expression in both the liver and mouse decidua on Day 7 of pregnancy [29]. We therefore asked whether Ptx3 induction follows that of Il1b in this system. Our Northern blot analysis shows that LPS induces Il1b expression in the liver and decidua maximally at 1 h after injection (Fig. 4A). While Ptx3 expression, as expected, was not induced in the liver, its expression was maximally elevated in Day 7 implantation sites (IS) at 2 and 6 h following LPS injection (Fig. 4A). These results suggest that IL1B is an inducer of Ptx3 in the uterus during early pregnancy.
|
To address whether endogenous IL1B is involved in inducing the unique expression pattern of Ptx3 in the uterus, we examined the spatiotemporal expression of Il1b in the peri-implantation uterus using in situ hybridization. Il1b is expressed abundantly but in a punctate pattern on Day 1 of pregnancy in the luminal epithelium (Fig. 4B), perhaps participating in the acute inflammatory response known to occur in the uterus after coitus [30]. Il1b expression is undetectable on Day 4, the day of uterine receptivity. However, its expression appears in stromal cells immediately underneath the luminal epithelium at the site of blastocyst attachment on midnight of Day 4, and this pattern persists on Day 5 of pregnancy. Furthermore, its temporal expression pattern mimics that of Ptx3 in that it is undetectable on Day 6 but reappears on Days 7 and 8 of pregnancy, albeit in fewer cells (Fig. 4B).
IL1B is classically referred to as a marker for monocytes and macrophages. Such IL1B-expressing monocytes/macrophages are transiently found within the capillaries in the stromal bed at the implantation site on Day 5 of pregnancy in mice [31]. Our observed localization of Il1b in the subluminal stromal cells suggests a different source for this cytokine. Regardless of the source, however, the pattern of Il1b expression on midnight of Day 4 and Day 5 of pregnancy correlates with that of Ptx3, suggesting a role for IL1B in inducing uterine Ptx3 expression in a paracrine manner. Their spatial localization on Days 7 and 8, however, is somewhat different. Il1b expression is evident in scattered cells at both the mesometrial and antimesometrial poles (Fig. 4B), whereas expression of Ptx3 is more localized to the antimesometrial pole (Fig. 1B).
Uterine Il1b and Ptx3 Expressions are Associated with Blastocyst Activation
Our observation of both Il1b and Ptx3 expression in the stromal cells surrounding the implanting blastocyst led us to question whether implanting blastocysts regulate Il1b, and therefore Ptx3, expression locally in the uterus. This would suggest a role for PTX3 during the onset of implantation, supporting our observation of its higher expression at implantation sites (Fig. 1A). We used the delayed implantation model to identify whether Ptx3 is upregulated at the time of blastocyst activation for implantation. In situ hybridization was performed on serial uterine sections of dormant (P4 only) and activated (P4 + E2) wild-type uteri at 12 and 24 h following an injection of E2 (Fig. 5). We observed that uterine Il1b and Ptx3 expressions are undetectable surrounding dormant blastocysts and throughout the P4-primed uterus, whereas activation of blastocysts with the initiation of implantation by estrogen upregulates both Il1b and Ptx3 expression in stromal cells adjacent to implanting blastocysts 12 h after injection (Fig. 5). This finding is consistent with Ptx3 expression in stromal cells surrounding the implanting blastocyst on Day 4 midnight and Day 5 of pregnancy (Fig. 1B). Whereas Ptx3 expression in stromal cells surrounding the implanting blastocyst is maintained 24 h after injection, Il1b expression disappeared. Collectively, these results suggest that signaling arising from the implantation-competent blastocyst and/or uterus at the time of implantation switches on the IL1B-PTX3 signaling pathway.
|
PTX3's role in the immune system is readily apparent, since Ptx3 null mice are more susceptible to select pathogens [8], and mice overexpressing Ptx3 have improved survival in response to endotoxic shock and sepsis [21]. Studies in Ptx3-null mice have also shown its important role in female fertility, specifically in cumulus-oocyte interactions during ovulation, impacting fertilization [7, 8]. Our present study showing Ptx3 expression in stromal cells at the time of blastocyst attachment on Day 4 (2400 h) of pregnancy, its persistent expression through Day 5 during the PDZ formation, and the observed compromised implantation and decidualization in Ptx3-null females suggests that PTX3 plays a crucial role in implantation and decidualization. PTX3 could be involved in protecting the embryo from maternal immunologic or other blood-borne noxious stimuli before the establishment of the avascular PDZ barrier. This is consistent with its disappearance on Day 6, when the PDZ is fully established. The appearance of Ptx3 at the border of the PDZ and SDZ on Days 7 and 8 also implies an embryo protective role, since PDZ cells undergo demise around this time to make room for the growing embryo.
Alternatively, PTX3 could also play a role in the formation of the PDZ, which begins to form late on Day 5, with its full establishment on Day 6 [26], the day that Ptx3 expression disappears. Since PTX3 is known to play a role in clearing apoptotic cells [21], it could serve to clear dying PDZ cells during this time. It is also known that PTX3 inhibits FGF2-dependent angiogenesis and proliferation [19, 20]. Since Fgf2 is also expressed in cells immediately surrounding the embryo upon its attachment to the uterus [32], perhaps PTX3 acts to counter FGF2-induced angiogenesis to contribute to the avascular nature of the PDZ and differentiation of stromal cells to form this zone [19, 26]. These putative roles of PTX3 could explain the reason for implantation and decidualization failure in Ptx3-null mice.
The significance of Ptx3 expression on Days 7 and 8 of pregnancy is not clearly understood. On these days, Ptx3 is specifically expressed at the boundary between the PDZ and SDZ. Perhaps PTX3 serves as a barrier between the degenerating PDZ and proliferating SDZ on these days. It is also possible that PTX3 present at the interface regulates cell death in the PDZ and differentiation of decidualizing stromal cells in the SDZ. This is consistent with findings showing PTX3's role in the clearance of apoptotic cells and activation of the complement cascade [9, 17, 18, 20]. PTX3 has also been characterized as a marker of human inflammatory conditions, and studies suggest a protective role for PTX3 at sites of inflammation, perhaps to prevent autoimmune reactions [17, 21]. The underlying cause and meaning of the abrupt disappearance of Ptx3 expression from Day 9 onwards is not clearly understood. It is possible that other immunologic or physiologic fetoplacental factors are in place to protect the developing embryo at this time.
Our finding that LPS stimulates Il1b expression to induce Ptx3 in decidua of Day 7 pregnant mice implies that IL1B is an inducer of PTX3 in vivo. In fact, Il1b appears in stromal cells immediately surrounding the implanting blastocyst, with Ptx3 expressed in stromal cells a few cell layers away, suggesting that IL1B induces Ptx3 expression in neighboring stromal cells. Furthermore, similar to Ptx3 expression, Il1b expression is concentrated at implantation sites compared with interimplantation sites, and both are expressed with the initiation of the blastocyst attachment by estrogen in a delayed implantation model. In the same vein, there is a recent report showing that signals emanating from trophoblast cells upregulate decidual Ptx3 expression in humans [23]. It is, however, possible that other factors play a role in inducing PTX3 during decidualization. We speculate that implantation-related stimuli arising from the blastocyst and/or uterus cooperate to induce Ptx3 expression. This question is currently under investigation in our laboratory.
Our present study illustrates for the first time an important role for uterine PTX3 in implantation and decidualization. These results have clinical implications, since PTX3 is expressed in the receptive endometrium, and trophoblast cells influence decidual PTX3 expression in humans [22, 23].
ACKNOWLEDGMENTS
We are grateful to Martin M. Matzuk (Baylor College of Medicine, Houston, TX) for providing us with Ptx3-null mice, to Fuhua Xu for assistance with statistical analysis, and to Sung Tae Kim for assistance with cloning.
FOOTNOTES
3Current address: Department of Animal Science and Technology, Beijing University of Agriculture, Beijing, China. 
1Supported in part by National Institute of Child Health & Human Development grants HD 12304 (to S.K.D.) and HD050315 (to H.W.). S.T. is supported by a National Institutes of Health National Research Service Award individual pre-doctoral fellowship from the National Institute of Drug Abuse (F31 DA021062).
Correspondence: 2Sudhansu K. Dey, Department of Pediatrics, Division of Reproductive and Developmental Biology, Vanderbilt University Medical Center, MCN-D4100, Nashville, TN 37232-2678. FAX: 615 322 4704; e-mail: sk.dey{at}vanderbilt.edu
Received: 21 April 2007.
First decision: 14 May 2007.
Accepted: 30 May 2007.
REFERENCES
This article has been cited by other articles:
|
|
 |
|
  R. M. Popovici, M. S. Krause, J. Jauckus, A. Germeyer, I. S. Brum, C. Garlanda, T. Strowitzki, and M. von Wolff The Long Pentraxin PTX3 in Human Endometrium: Regulation by Steroids and Trophoblast Products Endocrinology, March 1, 2008; 149(3): 1136 - 1143. [Abstract] [Full Text] [PDF]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
