Expression of laminin and nidogen genes during the postimplantation development of the mouse placenta

The expression patterns of laminin A, B1, B2, and nidogen genes were identified by in situ hybridization in postimplantation mouse extraembryonic tissues and maternal decidua during the period when the chorioallantoic placenta is established. Laminin and nidogen genes were not coordinately expressed either in the decidua or in trophoblast cells, indicating that these genes are regulated independently in these cell types during the establishment of the placenta. Laminin A mRNA was absent from the decidua except in the outer layer of cells adjacent to the myometrium and in the central decidual zone adjacent to the remnant of the uterine epithelium on Day 9. At this stage laminin B1, B2, and nidogen genes were strongly expressed in these cells and also in other regions of the decidua. Laminin B1 mRNA was present at higher levels in the decidua capsularis than in the decidua basalis, while nidogen mRNA showed highest expression in the decidua basalis. Laminin B2 mRNA was produced uniformly throughout the decidua at very high levels, suggesting that laminin B2 chains may be an important component of the decidual matrix. By Day 11, the nidogen gene was expressed only in endothelial cells lining the maternal blood spaces within the decidua. Laminin B1 and nidogen mRNAs were found at high levels within trophoblast giant cells at all stages, while laminin A mRNA was detected in trophoblast giant cells at later stages and laminin B2 mRNA was not produced in high levels by these cells. The patterns of gene expression show a very high degree of regional specialization, suggesting that the extracellular matrices in different regions of the decidua and extraembryonic membranes are likely to be composed of quite different ratios of laminin and nidogen polypeptides.(ABSTRACT TRUNCATED AT 250 WORDS)     

Trophic effects of myeloid leukaemia inhibitory factor (LIF) on mouse embryos

Myeloid leukaemia inhibitory factor (LIF) is expressed at highest concentrations in the maternal endometrial glands at about the stage of blastocyst implantation. LIF is also expressed by the extraembryonic membranes of the early mouse embryo. Embryos of different ages were cultured with, or without, LIF, and embryo growth in vivo and in vitro was examined to determine whether LIF is important for embryo development. Supplementing embryo culture media with 1000 U recombinant human LIF ml-1 increased the number of eight-cell mouse embryos developing beyond the hatched blastocyst stage in vitro from 62.1% to 85.1% (P < 0.05). LIF significantly increased the number of embryos hatching (33.8% versus 7.65% for controls 96 h after hCG injection, P < 0.001), completely hatching (85.1% versus 62.1%, P < 0.05), and exhibiting trophoblast outgrowth (13.5% versus 0% 120 h after hCG treatment, 85.1% versus 47.0% 144 h after hCG treatment, P < 0.001) in vitro. LIF-treated embryos also displayed a significantly greater area of trophoblast outgrowth than did controls as early as day 5 in culture (P < 0.005). These data show that LIF enhances mouse eight-cell embryo development in vitro, as seen by the accelerated rate of embryo hatching and trophoblast outgrowth. In addition, enhanced embryo survival in vivo is shown, following the transfer of LIF-treated embryos into a pseudopregnant recipient female. Expression of mRNA encoding LIF was detected in endometrial cells cultured in monolayer from uteri of day 3 pregnant females, explaining the known embryotrophic effects of endometrial coculture. This expression was not enhanced significantly by treatment with oestradiol (3.7 x 10(-5) mol l-1) or progesterone (3.2 x 10(-6) mol l-1) or both hormones. These results indicate that LIF could have a dual action in early embryogenesis as an embryotrophin and as a factor required for embryo implantation. Multiple roles for LIF are consistent with the expression of this factor at embryonic, extraembryonic and maternal sites during early embryogenesis.     

Quantitative assay system for specific enzyme activity using antibody: the case of protease, subtilisin BPN''

Syndecan-1 is a cell surface heparan sulphate proteoglycan, which binds to the extracellular matrix (ECM), growth factors and antithrombin III. The early expression of syndecan-1 during mouse embryonic development suggests a potential role in the communication between the embryo and the ECM of decidua. Using immunohistochemical methods, the present study showed that the expression of syndecan-1 in the trophoblast cells changes along trophoblast differentiation. The syncytiotrophoblasts in the chorionic villi exhibited an apical expression of syndecan-1. This suggests that the expression is restricted to non-migrating, non-proliferating trophoblasts. The mode of syndecan-1 expression by human placental trophoblasts is independent of gestational age. The expression is not changed in miscarriages. In pre-eclampsia, the staining for syndecan-1 on the villous syncytiotrophoblast is weaker compared to normal pregnancy, but in placental bed the expression is similar. The unique apical localization of syndecan-1 in chorionic villi, not detected in any other tissues, suggests a potential role in fetomaternal communication probably via growth factor binding and in anticoagulation of intervillous circulation.     

Two-parameter flow fluorescence analysis of human chromosomes. Quantitative processing]

Adrenomedullin (AM) is a newly discovered hypotensive peptide which is believed to play an important role for blood pressure control in the adult. Although it has been well established that a major production site of AM is vascular endothelial cells, we now show that AM is most highly expressed in trophoblast giant cells, which are derived from the conceptus and are directly in contact with maternal tissues at the implantation site. Northern blot and in situ hybridization analyses show that the AM mRNA begins to be detected just after implantation and its level peaks at 9.5 days postconception (d.p.c.) in those cells. Expression then falls dramatically after 10.5 d.p.c., coincident with the completion of the mature chorioallantoic placenta. Immunohistochemical analyses show that the AM peptide is secreted from the trophoblast giant cells into the surrounding tissues, i.e., embryo, decidua, and maternal circulation. In contrast, the expression of an AM receptor was not detected by Northern blot analyses in either embryo or trophoblast giant cells at 7 d.p.c., when the AM gene is most highly expressed in the trophoblast giant cells. This suggests that the AM produced and secreted from the embryo's trophoblast giant cells acts on the maternal tissues rather than on the embryonic tissues. Based on these results, we propose that the high production of AM may be the mechanism by which the embryos survive at the early postimplantation period by pooling maternal blood in the implantation site in order to secure nutrition and oxygen before the establishment of efficient embryo-maternal circulation through the mature placenta.     

Identification of ''tissue'' transglutaminase binding proteins in neural cells committed to apoptosis

Mice in which the gene that encodes the receptor (R) for leukemia inhibitory factor (LIF) has been deleted show abnormal growth and development of the placenta. This indicates that LIF plays an important role in placental development. The expression of LIF-R and LIF was examined in human trophoblast and decidua using in situ hybridization and immunocytochemistry. LIF-R mRNA and immunoreactivity was localized in villous and extravillous trophoblast throughout pregnancy, and in endothelial cells of the fetal villi. Strong expression of mRNA encoding LIF was detected in decidual leukocytes, which are abundant at the implantation site. Extravillous trophoblast, which invades the maternal decidua, therefore expresses LIF-R as it moves past decidual leukocytes, which express LIF mRNA. The effect of LIF on cultured human trophoblast was examined in vitro. Recombinant human LIF had no effect on [3H]thymidine incorporation by purified extravillous trophoblast, nor on expression of integrins alpha1, alpha5, or beta1 by isolated trophoblast. These results identify fetal endothelial cells and all cells of the trophoblast lineage as targets for the action of LIF in human placenta. Although its effects on trophoblast are not yet clear, LIF appears to mediate interactions between maternal decidual leukocytes and invading trophoblast. LIF may also play a critical role in controlling angiogenesis in the placental villi, since human fetal endothelial cells express LIF-R, and mice lacking a functional LIF receptor gene show altered vascular development in the placenta.     

Differential nm23 gene expression at the fetal-maternal interface

The product of the nm23 gene has been proposed as a candidate tumour metastasis suppressor protein. A strong association has been observed between reduced expression of the nm23 gene and acquisition of metastatic behaviour in some tumour cells, including breast cancer and melanoma, but not in others, such as neuroblastoma and colon, cervical and thyroid cancers. During the early gestation period both human and murine trophoblast cells exhibit in vitro invasive properties similar to those of neoplastic cells. Such invasive properties, however, disappear in the late stage of gestation. In the present study, we examined the abundance of nm23 mRNA from various fetal-maternal interface tissues (uterus, decidua, placenta and embryo) during early (day 8), mid (day 14) and late (day 18) stages of gestation in CD1 mice, in order to determine whether nm23 plays any anti-invasive and/or biological roles during gestation. nm23 was found to be expressed in all the tissues during the early and mid stages of gestation. The expression levels were, however, variable among different tissues and development stages. In the early stage, nm23 mRNA levels were the highest and similar among tissues from the uterus, decidua, placenta and embryo. In the mid stage, the mRNA levels were reduced significantly in the uterus, decidua and placenta, but not in the embryo. In the late stage, nm23 mRNA was further reduced to the extent that it could not be seen in the decidua, was barely seen in the uterus and was weakly present in the placenta. However, the mRNA level of the embryo in the late stage was still high and similar to the early stage. We also examined nm23 expression in trophoblast cells from normal human term placenta and a highly metastatic human choriocarcinoma cell line, JAR. nm23 expression was significantly higher in JAR than in normal placenta, indicating that nm23 does not appear to have an anti-metastatic function in this cell line. Several cytokines--interleukin 2 (IL-2), tumour necrosis factor alpha (TNF-alpha) and interferon gamma (IFN-gamma)--and prostaglandin E2 (PGE2) known to modulate tumour growth and metastasis were examined to determine whether they regulate nm23 expression in JAR in vitro. The B16F10 melanoma cell line was used as control. No effect was found in the JAR cell line, whereas TNF-alpha, IFN-gamma and PGE2 down-regulated nm23 expression in the B16F10 cell line.(ABSTRACT TRUNCATED AT 400 WORDS)     

Implantation and decidualization in rodents

This article reviews the main events of embryo-implantation and decidualization in rodents. In common laboratory rodents the embryo attaches to the uterine epithelial lining, usually on days 4 to 6 of pregnancy. A progressive degree of proximity between trophoblast and epithelium occurs until the epithelial cells undergo apoptosis and detach from the basement membrane. During the attachment stage, the spindle-shaped connective tissue cells that underlie the epithelium next to the embryos transform into polyhedral and closely packed decidual cells. Following the epithelial detachment and the breaching of the basement membrane the embryo is thus in direct contact with decidual cells. These cells accumulate organelles associated with synthesis of macro-molecules, intermediate filaments, and eventually lipid droplets and glycogen. Another remarkable feature of decidual cells is the establishment of gap and adherens intercellular junctions. Differentiation of fibroblasts into decidual cells advances antimesometrially and mesometrially, creating in the endometrium several regions of cells with different morphology. The whole phenomenon of decidualization which is normally triggered by the embryo can be artificially induced in pseudo-pregnant or hormonally-prepared animals with the use of diverse stimuli. The uterine epithelium is probably responsible for the transduction of the initial stimulus. Prostaglandins have been shown to be important in the induction of decidualization. More recently other substances such as leukotrienes, platelet-activating factor (PAF), and transforming growth factor (TGF) have been thought to play a role in induction. Much evidence points to prostaglandin production by the decidual cells. New proteins such as a luteotropic factor, desmin, and other molecules were shown to be produced after rat stromal cells undergo decidual transformation. The extracellular matrix of the mouse decidua contains very thick collagen fibrils. Mouse decidual cells are also very active in phagocytosing the thick fibrils, contributing to the remodeling and involution of the decidua that accompanies embryonic growth. Radioautographic data indicates that mouse decidual cells produce and secrete collagen and sulfated proteoglycans.     

Expression of insulin-like growth factor-II and IGF-binding protein-1 mRNAs in term rhesus monkey placenta: comparison with human placenta

The patterns of expression insulin-like growth factor-II (IGF-II) and IGF-binding protein-1 (IGFBP-1) mRNAs were compared between term human and rhesus monkey placenta using in situ hybridization histochemistry. Since IGFs and IGFBPs are paracrine factors, the identification of the sites of synthesis of the IGFs and their binding proteins indicate the potential sites of biological action. In both species, IGF-II mRNA was found in highest abundance in the extravillous cytotrophoblasts. The major difference was observed in placental villi. In the human placenta, IGF-II mRNA was expressed in the chorionic mesoderm of the placental villi, whereas, in the rhesus placenta, it was expressed in the syncytiotrophoblasts and not in the chorionic mesoderm. In both species, IGFBP-1 mRNA was expressed only in the decidua. Therefore, the pattern of expression of IGFBP-1 mRNA in the maternal decidua is similar between rhesus monkey and human placenta, but that of IGF-II mRNA in the fetal placental villi is different. These data suggest that the IGF-II-IGFBP-1 interaction in the paracrine regulation of placental growth and/or function in the rhesus monkey and human placentae may have similarities and differences.     

Vasoactive intestinal peptide is an important endocrine regulatory factor of fetal rat testicular steroidogenesis

This study elaborates our recent preliminary finding that vasoactive intestinal peptide (VIP) has a specific stimulatory effect on fetal rat Leydig cells. We examined the dose-response relationship for the effect of VIP on cAMP and testosterone production by dispersed fetal Leydig cells isolated from rat testes on embryonic day (E) 18.5. Further, we used RT-PCR to examine the expression of the VIP gene in fetal brain and testes and that of the VIP receptor genes in fetal testes and used RIA to measure VIP in testes and plasma during the fetal period. VIP stimulated fetal testicular cAMP production at a dose of 10(-9) mol/liter, whereas a dose as low as 10(-12) mol/liter stimulated testosterone production. This suggests that VIP at low doses may stimulate testosterone production using second messenger pathways other than cAMP. RT-PCR analysis could not reveal either VIP messenger RNA (mRNA) in fetal tissues or VIP1 receptor mRNA in the fetal or newborn testes, whereas VIP2 receptor mRNA was detected in fetal testes as early as E15.5. Northern hybridization analysis showed that the level of expression of VIP2 receptor mRNA is very low in fetal and neonatal testes and increases with age. The testicular VIP content was unmeasurable by our RIA method (i.e. <1 fmol/testis), whereas the circulating level of VIP was 82.9 +/- 1.1 pmol/liter on E17.5 and decreased with advancing fetal age. In conclusion, our results suggest that VIP from an extratesticular source, possibly from the maternal compartment, may regulate fetal testicular steroidogenesis through type 2 receptors as early as E15.5. These findings may be of physiological significance, because the onset of fetal testicular steroidogenesis occurs at an age (E15.5-19.5) before the onset of pituitary LH secretion.     

Immunohistochemical analysis of insulin-like growth factor-binding proteins -1, -2, and -3 in implantation sites of the mouse

PURPOSE: Our purpose was to analyze potential interactions between the embryo and the maternal endometrial interface in vivo by analyzing immunolocalization of insulin-like growth factor-binding proteins (IGFBPs) -1, -2, and -3 in implantation sites of the mouse. METHODS: Six-week-old B6D2F1 female mice underwent superovulation followed by mating and sacrifice at timed intervals. Formalin-fixed paraffin-embedded tissue was used for avidin-biotin immunocytochemical localization of IGFBPs utilizing standard methodology. RESULTS: Immunostaining at 1.5 days post coitum revealed light staining in the epithelial glandular cells and faint staining in decidual stroma for both IGFBP-1 and IGFBP-2. At 7.5-10.5 days post coitum, there was moderate-dense immunostaining in the decidualized stromal cells at the implantation site for all three IGFBPs, whereas light immunostaining was seen in nonimplantation site decidua. CONCLUSIONS: Compartmentalization of immunostaining for IGFBP-1, -2, and -3 within decidualized stroma suggests that these proteins may be regulated by trophoblastic and/or embryonic signals.     

Control of secretory leukocyte protease inhibitor gene expression in the porcine periimplantation endometrium: a case of maternal-embryo communication

The contributions of the conceptus (embryo and associated membranes) and of the maternal endocrine milieu to control of endometrial secretory leukocyte protease inhibitor (SLPI, also designated antileukoproteinase) expression during the periimplantation stages of embryo development were examined in the present study. Uterine endometrium from distinct sites was collected from pigs at Days 16-25 of pregnancy and analyzed for steady-state SLPI mRNA levels. Endometrium situated directly beneath conceptuses (mesometrial) had greater (p < 0.05) SLPI mRNA levels than that obtained from antimesometrial and interimplantation sites and myometrium. This site-specific difference was most pronounced during late (Days 19-21) and post (Days 23-25)-implantation stages and was also observed, albeit to a lesser degree, for the mRNA encoding uteroferrin (Uf). Conditioned medium (CM; 50% v:v) from Day 21, but not Day 12, conceptuses increased (p < 0.05) SLPI mRNA levels, while neither CM affected mRNA levels for Uf and several other genes expressed in endometrial explants. One inducing factor in Day 21 CM was characterized as a low-molecular-mass (< 12 kDa), relatively heat-stable protein. Transforming growth factor (TGF alpha) increased (p < 0.05), epidermal growth factor (EGF) tended to increase (p = 0.10), and insulin-like growth factor (IGF)-I and IGF-II had no effect (p > 0.10) on, SLPI mRNA levels in Day 12 endometrial explants. Medium conditioned by the pig trophoblast cell line, Jag-1, but not by other mammalian cell lines, had SLPI inducer activity. The maternal endocrine contribution to SLPI gene expression was examined using freshly isolated and short-term-cultured Day 12 and Day 21 pregnant pig endometrium. Steady-state SLPI mRNA levels were increased (p < 0.05) in Day 12, but not Day 21, tissues upon short-term culture in serum-free medium. This increase was time dependent, was similarly demonstrated for Uf mRNA, was not observed in corresponding lung and liver, and was inhibited by inclusion of serum from pigs of diverse endocrine status. In summary, two potential modulators of endometrial SLPI gene expression were identified: 1) a conceptus-derived low-molecular-mass protein, possibly TGF alpha, that mediates in part the up-regulation of SLPI gene expression in endometrium closely associated with implantation sites, and 2) an inhibitory component(s) present in maternal serum. Results suggest opposing actions of maternal and embryonic factors at the maternal-embryo interface and highlight involvement of the periimplantation embryo in directing the spatiotemporal expression of endometrial genes implicated in its development.     

Growth control of embryonic stem cells injected into mouse uterus on fifth day of pregnancy

Previous studies have shown that embryonic stem cells (ES) may participate in normal embryonic development when they are injected into the blastocyst. In contrast, ES cells develop into tumors if injected in ectopic sites in adult mice. In this study we injected ES-D3 cells, with the LacZ gene incorporated, into 5-day pregnant mouse uteri, into pregnant unilaterally salpingectomized uteri, into pseudopregnant uteri and into non-pregnant uteri. X-gal staining enabled us to identify injected ES cells on the 7th, 9th, 10th, 12th and 15th days post-injection. In pregnant decidua, the ES cells were located initially in the mesometrial decidua and later distributed in the basal and capsular decidua and in the endodermic layer of the visceral yolk sac. In pregnant, unilaterally salpingectomized mouse uteri, ES cells were mainly located in the uterine lumen and tumors were not observed in either case. In contrast, ES cells injected into pseudopregnant uteri often developed into tumors and those injected into non-pregnant uteri always developed into teratocarcinomas. We conclude that the pregnant-uterine microenvironment may participate in the control of ES cell growth.     

Development of nicotinic receptor clusters and innervation accompanying the change in muscle phenotype in the mouse esophagus

During development, the external muscle of the mouse esophagus undergoes a transdifferentiation from smooth to striated muscle (Patapoutian et al. [1995] Science 270:1818-1821). We now report on the development of the innervation accompanying the change in phenotype of the external muscle of the mouse esophagus. The phenotype of the muscle was monitored by using light and electron microscopy. Nicotinic acetylcholine receptors were localised by using a fluorescence conjugate of alpha-bungarotoxin, and neural elements were localised by using antisera to synaptophysin (a synaptic vesicle protein that was used to label all nerve terminals), the vesicular acetylcholine transporter (VAChT), calcitonin gene-related peptide (CGRP), nitric oxide synthase (NOS), and vasoactive intestinal peptide (VIP). CGRP and VAChT were co-localised in the terminals of vagal motoneurons that innervate the external muscle, and NOS and VIP were co-localised in intrinsic (enteric) neurons, which provide some terminals that are associated with motor endplates. Cells exhibiting striations were first observed in the outer layers of the most rostral regions of the esophagus of embryonic day 15 (E15) mice. Clusters of nicotinic acetylcholine receptors were also first observed at the rostral end of the esophagus of E15 mice, and developed in a rostrocaudal progression that coincided with the appearance of striations within the muscle cells. Synaptophysin-, VAChT- and NOS-immunoreactive nerve terminals were present within the external muscle prior to the formation of receptor clusters, and their appearance did not follow any apparent rostrocaudal sequence. Surprisingly, not all of the receptor clusters at E15 had synaptophysin- and VAChT-immunoreactive nerve terminals closely associated with them. However, from E18 on, almost all of the clusters had synaptophysin-immunoreactive nerve terminals in close association. At late embryonic and early postnatal stages, there was a rostrocaudal gradient in the proportion of receptor clusters having VAChT-immunoreactive nerve terminals associated with them. Nerve terminals associated with nicotinic receptor clusters did not show detectable CGRP-immunoreactivity until one to two weeks after the appearance of synaptophysin- and VAChT-immunoreactivity. The NOS-immunoreactive neurons did not show detectable VIP-immunoreactivity until three days after NOS could be detected. These results show that the appearance of clusters of nicotinic receptors in the external muscle of the esophagus coincides with the expression of a striated muscle phenotype, but not with the presence of ingrowing nerve terminals. However, many of the receptor clusters that were observed first were apparently uninnervated.     

Nutrition management, nitrogen efficiency, and income over feed cost on dairy farms in Costa Rica

In a previous study, insulin-like growth factor-I (IGF-I) and a potential inhibitory binding protein, IGF binding protein-4 (IGFBP-4), were found to be expressed in a cell-specific and temporally dynamic manner in the mouse uterus during the periimplantation period. The mRNA levels of both IGF-I and IGFBP-4 rapidly increased between Days 5 and 6 of gestation and then declined after the establishment of embryo implantation. In the current study, we conducted in situ hybridization analysis on pregnant mouse uteri and deciduomata-induced mouse uteri to determine whether the presence of an embryo is required for uterine IGF-I and IGFBP-4 mRNA expression. Our data reveal that before implantation, the maternal hormones of pregnancy support IGF-I and IGFBP-4 mRNA expression. Beyond gestational Day 4, however, decidualization of the uterine stroma, either artificially induced or naturally induced by an implanting embryo, is sufficient for maintaining the expression of these two genes. Thus, the presence of specific embryo factors is not required for IGF-I and IGFBP-4 expression in the periimplantation uterus. These studies indicate that the expression of IGF-I and IGFBP-4 mRNAs may be associated with decidualization of uterine stromal cells. The restricted anatomical and temporal expression of IGF-I and IGFBP-4 mRNAs in the periimplantation uterus suggests a physiologic role for IGF-I and IGFBP-4 in the maintenance and expansion of decidualization.     

Expression of leukaemia inhibitory factor (LIF) receptor in human placenta: a possible role for LIF in the growth and differentiation of trophoblasts

Leukaemia inhibitory factor (LIF) is a cytokine that displays multiple activities in various tissues and is essential for blastocyst implantation in mice. In the human uterus, LIF is expressed in endometrial tissue and the decidua. To elucidate the role it plays, the mRNA levels for two LIF receptor (R) subunits, LIF-R and gp130, were examined in human endometrium, placenta and decidua by Northern blot hybridization. The expression of LIF-R gene was detected in the chorionic villus during the first trimester, in term placenta, and at lower levels in the decidua. The expression of LIF-R gene was not detectable in non-pregnant endometrium. The expression of the gp130 gene was detected in all tissues examined. During pregnancy, there was no significant change in the mRNA concentration of LIF-R in the placenta, while that of gp130 increased after the second trimester. The human choriocarcinoma cell line, BeWo, was found to express LIF-R and gp130. LIF inhibited forskolin-induced human chorionic gonadotrophin (HCG)-beta production by BeWo in a dose-dependent manner, and it ameliorated forskolin-induced growth suppression. These findings suggest that LIF plays a regulatory role in trophoblast growth and differentiation during pregnancy in human placenta.     

Maternal IL-11Ralpha function is required for normal decidua and fetoplacental development in mice

In eutherian mammals, implantation and establishment of the chorioallantoic placenta are essential for embryo development and survival. As a maternal response to implantation, uterine stromal cells proliferate, differentiate, and generate the decidua, which encapsulates the conceptus and forms the maternal part of the placenta. Little is known about decidual functions and the molecular interactions that regulate its development and maintenance. Here we show that the receptor for the cytokine interleukin-11 (IL-11Ralpha) is required specifically for normal establishment of the decidua. Females homozygous for a hypomorphic IL-11Ralpha allele are fertile and their blastocysts implant and elicit the decidual response. Because of reduced cell proliferation, however, only small deciduae form. Mutant deciduae degenerate progressively, and consequently embryo-derived trophoblast cells generate a network of trophoblast giant cells but fail to form a chorioallantoic placenta, indicating that the decidua is essential for normal fetoplacentation. IL-11Ralpha is expressed in the decidua as well as in numerous other tissues and cell types, including the ovary and lymphocytes. The differentiation state and proliferative responses of B and T-lymphocytes in mutant females were normal, and wild-type females carrying IL-11Ralpha mutant ovaries had normal deciduae, suggesting that the decidualization defects do not arise secondarily as a consequence of perturbed IL-11Ralpha signaling defects in lymphoid organs or in the ovary. Therefore, IL-11Ralpha signaling at the implantation site appears to be required for decidua development.     

Fertility impairment in granulocyte-macrophage colony-stimulating factor-deficient mice

Granulocyte-macrophage colony-stimulating factor (GM-CSF) has been identified as a potentially important mediator of intercellular communication in the female reproductive tract, with principal target cells being the large populations of myeloid leukocytes in the cycling and pregnant uterus, the preimplantation embryo, and trophoblast cells of the developing placenta. To determine the physiological significance of this cytokine in reproduction, the fertility of genetically GM-CSF-deficient (GM-/-) mice was examined. Implantation rates were normal in GM-/- mice, and viable pups were produced. However, the mean litter sizes of GM-/- x GM-/- breeding pairs were 25% smaller at weaning than those of GM+/- x GM+/- pairs, due to fetal death late in gestation and early in postnatal life, with a disproportionate loss of male pups. On Day 17 of pregnancy, the mean number of resorbing and malformed fetuses was twice as high in pregnant GM-/- females (21%, vs. 11% in GM+/- females); the mean fetal weight and the mean fetal:placental ratio in surviving conceptuses were diminished by 7% and 6%, respectively; and the number of very small fetuses (< 500 mg) was 9-times as high (23% vs. 2.5%). Mortality during the first 3 wk of life was 4.5-times as high in pups born to GM-/- mothers (9%, vs. 2% in GM+/- females), and diminished size persisted in GM-/- pups, particularly males, into adulthood. The detrimental effect of maternal GM-CSF deficiency was less apparent when GM-/- females were mated with GM+/+ males; litter sizes at birth and at weaning were not significantly smaller than in GM+/- matings, and fetal weights and fetal:placental ratios were also comparable. When polymerase chain reaction was used to genotype embryonic tissue in heterozygote matings, GM-/- fetuses from GM-/- females were found to be smaller than their GM+/- littermates and smaller than GM-/- fetuses gestated in GM+/- females. The size and distribution of uterine granulocyte and macrophage populations were normal during the estrous cycle, during early pregnancy, and in midgestation. Analysis of placental structure revealed that the ratio of labyrinthine to spongiotrophoblast areas was reduced by approximately 28% in GM-/- placentae, and the proportion of vacuolated trophoblast "glycogen cells" in the spongiotrophoblast layer was diminished. Compromised placental function as a result of subtle developmental aberrations may therefore partially account for embryonic growth retardation in GM-CSF-deficient mice. Collectively, these studies show that fetal growth and viability are jeopardized in the absence of maternal GM-CSF. The detrimental effects are most clearly evident when the conceptus is also GM-CSF deficient, suggesting that GM-CSF of either maternal or fetal origin is required for optimal growth and survival of the fetus in mice.