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  • Abstract: placenta x
  • Abstract: chorioallantoic x
  • Abstract: trophoblast x
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  • Abstract: human placental lactogen x
  • Abstract: syncytium x
  • Abstract: decidualization x
  • Abstract: decidua x
  • Abstract: human chorionic gonadotropin x
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Free access

LJ Xiao, HL Diao, XH Ma, NZ Ding, K Kadomatsu, T Muramatsu and ZM Yang

Basigin is essential for fertilization and implantation. The aim of this study was to determine the expression and hormonal regulation of the basigin gene in the rat uterus during the peri-implantation period. Basigin mRNA was localized strongly in the luminal epithelium on day 1 of pregnancy and gradually decreased to a basal concentration from day 3 to day 5 of pregnancy. Basigin mRNA and protein were expressed strongly in the implanting blastocyst and primary decidua on day 6 of pregnancy. A similar expression pattern was also induced in the uterus after delayed implantation was terminated by oestrogen treatment and the embryo implanted, whereas expression was not detected during delayed implantation. Basigin expression was not detected on day 6 of pseudopregnancy. Basigin mRNA was expressed strongly in the decidua on days 7 and 8 of pregnancy. Furthermore, both basigin mRNA and protein were induced in the decidua during artificial decidualization. In addition, oestrogen stimulated strong expression of basigin mRNA in the uterine epithelium of ovariectomized rats. These findings indicate that basigin may play a role during implantation and decidualization in rats.

Free access

Rebecca L Jones, Tu’uhevaha J Kaitu’u-Lino, Guiying Nie, L Gabriel Sanchez-Partida, Jock K Findlay and Lois A Salamonsen

Maternal–fetal communications are critical for the establishment of pregnancy. Embryonic growth and differentiation factors produced by the oviduct and uterus play essential roles during the pre- and early post-implantation phases. Although several studies indicate roles for activin in embryonic development, gene-knockout studies have failed to identify a critical role in mammalian embryogenesis. We hypothesized that activin is produced by maternal tissues during the establishment of pregnancy, and thus maternally derived activin could compensate for the absence of embryonic activin in null homozygotes during critical developmental stages. We investigated the expression of inhibin α, activin βA, and βB subunits in the mouse oviduct and uterus during the estrous cycle and early pregnancy, and in the early conceptus. Inhibin α subunit was weakly expressed, while activin βA and βB subunits were strongly expressed in oviduct and uterus at estrous, and dramatically upregulated in the uterus on each day of pregnancy between days 3.5 and 8.5 post coitum. Prior to implantation, activin βA and βB subunits were immunolocalized to oviductal and uterine epithelial cells; following implantation they were expressed in the stroma, in a wave preceding decidualization. Later in pregnancy, activin βA and βB subunits were present in decidua basalis, trophoblast giant cells, and labyrinth zone of the developing placenta. Expression of activin βA subunit was also detected in blastocysts and early post-implantation embryos. These data are consistent with a role for maternally derived activins in the support of the pre-implantation embryo, and during gastrulation and embryogenesis.

Free access

Y. Yamamoto, M. Kurohmaru and Y. Hayashi

Summary. Mouse trophoblast and decidua were examined by means of immunohistochemistry to define the localization of type I interferon. The decidua were stained for type I interferon at the time of implantation. The strong reaction was first observed in the primary decidual zone on day 5 and subsequently in the secondary decidual zone on day 6. After day 10, the decidua basalis and decidua capsularis showed a strong reaction.

At the one-cell stage, embryos were weakly labelled, but a positive reaction was recognized in compacted morulae. Blastocysts on days 3 and 4 were positive in trophoblast and inner cell mass and a strong reaction was observed in the primitive endoderm on day 4. The visceral endoderm on day 5 and the trophoblast on day 6 were positive. After day 10, the trophoblast giant cells, labyrinth, visceral yolk sac and fetal blood cells gave a positive reaction.

This study is the first demonstration of type I interferon localization in situ in mouse trophoblast and decidua during decidual formation.

Keywords: type I interferon; implantation; decidualization; trophoblast; mouse

Open access

Patricia Grasa, Heidy Kaune and Suzannah A Williams

Female mice generating oocytes lacking complex N- and O-glycans (double mutants (DM)) produce only one small litter before undergoing premature ovarian failure (POF) by 3 months. Here we investigate the basis of the small litter by evaluating ovulation rate and embryo development in DM (Mgat1F/FC1galt1F/F:ZP3Cre) and Control (Mgat1F/FC1galt1F/F) females. Surprisingly, DM ovulation rate was normal at 6 weeks, but declined dramatically by 9 weeks. In vitro development of zygotes to blastocysts was equivalent to Controls although all embryos from DM females lacked a normal zona pellucida (ZP) and ∼30% lacked a ZP entirely. In contrast, in vivo preimplantation development resulted in less embryos recovered from DM females compared with Controls at 3.5 days post coitum (dpc) (3.2±1.3 vs 7.0±0.6). Furthermore, only 45% of mated DM females contained embryos at 3.5 dpc. Of the preimplantation embryos collected from DM females, approximately half were morulae unlike Controls where the majority were blastocysts, indicating delayed embryo development in DM females. Post-implantation development in DM females was analysed to determine whether delayed preimplantation development affected subsequent development. In DM females at 5.5 dpc, only ∼40% of embryos found at 3.5 dpc had implanted. However, at 6.5 dpc, implantation sites in DM females corresponded to embryo numbers at 3.5 dpc indicating delayed implantation. At 9.5 dpc, the number of decidua corresponded to embryo numbers 6 days earlier indicating that all implanted embryos progress to midgestation. Therefore, a lack of complex N- and O-glycans in oocytes during development impairs early embryo development and viability in vivo leading to delayed implantation and a small litter.

Free access

Xue-Chao Tian, Qu-Yuan Wang, Dang-Dang Li, Shou-Tang Wang, Zhan-Qing Yang, Bin Guo and Zhan-Peng Yue

The aim of this study was to examine the expression and regulation of the crystallin, alpha B (Cryab) gene in mouse uterus during the peri-implantation period by in situ hybridization and real-time PCR. There was no detectable Cryab mRNA signal on days 1–4 of pregnancy. On day 5 of pregnancy when embryo implanted, a high level of Cryab mRNA signal was found in the subluminal stroma surrounding the implanting blastocyst. On days 6–8, Cryab mRNA was strongly expressed in the primary decidua. By real-time PCR, a high level of Cryab expression was detected on days 7 and 8 of pregnancy, although Cryab expression was seen from days 1 to 8. Under in vivo and in vitro artificial decidualization, Cryab expression was significantly elevated. Compared with the progesterone-primed delayed implantation uterus, a high level of Cryab mRNA expression was observed in estrogen-activated implantation uterus. In the uterine stromal cells, cAMP, estrogen, and progesterone could induce the expression of Cryab gene. In the ovariectomized mouse uterus, estrogen could also induce the expression of Cryab while progesterone inhibited its expression. Our data suggest that Cryab may play an important role during mouse embryo implantation and decidualization and that estrogen and progesterone can regulate the expression of Cryab gene.

Free access

J. P. Hearn, G. E. Webley and A. A. Gidley-Baird

Summary. Genes for chorionic gonadotrophin (CG) are transcribed by the 16-cell embryo stage in humans, but there is no clear evidence of CG secretion as a bioactive dimer before attachment and trophoblast outgrowth stages of implantation. The studies summarized question the timing of CG expression and secretion, the possible roles of CG for intraembryonic differentiation and at the implantation site, and the recognition of this primate embryo-derived signal in support of the corpus luteum. The data suggest that the implantation window in primates may be broader than in nonprimate species, where a closer synchrony between embryonic, tubal and uterine events appears to be necessary for embryonic survival. Some preliminary data concerning an association between peripheral thrombocytopenia, ovarian inhibin secretion and peri-implantation stages of embryo development indicate that an unknown embryonic signal may be secreted before bioactive CG can be detected.

Keywords: chorionic gonadotrophin; corpus luteum; embryo; implantation; platelet-activating factor; inhibin; pregnancy; primate

Free access

NZ Ding, XH Ma, HL Diao, LB Xu and ZM Yang

The aim of this study was to examine the expression and regulation of peroxisome proliferator-activated receptor delta (PPARdelta) gene in rat uterus during early pregnancy by in situ hybridization and immunohistochemistry. PPARdelta mRNA expression in the luminal epithelium was high on day 1 of pregnancy, gradually declined from day 2 and was undetectable on day 5 of pregnancy. However, expression in the glandular epithelium began to increase from day 2 and was high on day 5 of pregnancy. There was no detectable PPARdelta immunostaining in the luminal and glandular epithelium from day 1 to day 5. On day 6 of pregnancy when embryos implanted, PPARdelta mRNA and immunostaining were intense in the subluminal stroma at implantation sites. On days 7 and 8, there was strong expression of both PPARdelta mRNA and intense immunostaining in the decidualized area near the lumen. There was low expression of PPARdelta in the subluminal stroma and glandular epithelium under delayed implantation. After delayed implantation was terminated by oestrogen treatment and embryo implantation was initiated, both PPARdelta mRNA and immunostaining were strongly induced in the subluminal stroma. Intense PPARdelta immunostaining was observed in the decidua under artificial decidualization, while no detectable immunostaining was seen in the uninjected control horn. Retinoid X receptor (RXRalpha) immunostaining was seen in the subluminal stroma surrounding the implanting blastocyst on day 6 and in the decidual cells on days 7 and 8 of pregnancy. In conclusion, the high PPARdelta expression at implantation sites and in the decidual cells in rat uterus indicates that PPARdelta may play an important role during implantation and decidualization.

Free access

THOMAS P. COWELL

Summary.

Four-day-old mouse embryos were transferred to the uterine lumen of virgin cyclic and ovariectomized mice; the eggs 'implanted' and developed only in mice whose endometrium was previously traumatized with a glass scraper. The histology of the mechanically induced implantation sites is described and similarities to normal implantation sites are discussed.

Implanted embryos developed only to stages equivalent to 5 to 9 days of normal pregnancy, but the trophoblast continued to proliferate and invaded the endometrium, eroding maternal blood vessels and distending the uterus. In five of eight ovariectomized mice, plaques of decidual-like cells were found near the trophoblast 7 to 12 days after transfer.

Free access

Hui Li, Yu-Han Meng, Wen-Qing Shang, Li-Bing Liu, Xuan Chen, Min-Min Yuan, Li-Ping Jin, Ming-Qing Li and Da-Jin Li

Chemokine CCL24, acting through receptor CCR3, is a potent chemoattractant for eosinophil in allergic diseases and parasitic infections. We recently reported that CCL24 and CCR3 are co-expressed by trophoblasts in human early pregnant uterus. Here we prove with evidence that steroid hormones estradiol (E), progesterone (P), and human chorionic gonadotropin (hCG), as well as decidual stromal cells (DSCs) could regulate the expression of CCL24 and CCR3 of trophoblasts. We further investigate how trophoblast-derived CCL24 mediates the function of trophoblasts in vitro, and conclude that CCL24/CCR3 promotes the proliferation, viability and invasiveness of trophoblasts. In addition, analysis of the downstream signaling pathways of CCL24/CCR3 show that extracellular signal-regulated kinases (ERK1/2) and phosphoinositide 3-kinase (PI3K) pathways may contribute to the proliferation, viability and invasiveness of trophoblasts by activating intracellular molecules Ki67 and matrix metallopeptidase 9 (MMP9). However, we did not observe any inhibitory effect on trophoblasts when blocking c-Jun N-terminal kinase (JNK) or p38 pathways. In conclusion, our data suggests that trophoblast-derived CCL24 at the maternal-fetal interface promotes trophoblasts cell growth and invasiveness by ERK1/2 and PI3K pathways. Meanwhile, pregnancy-related hormones (P and hCG), as well as DSCs could up-regulate CCL24/CCR3 expression in trophoblasts, which may indirectly influence the biological functions of trophoblasts. Thus, our results provide a possible explanation for the growth and invasion of trophoblasts in human embryo implantation.

Restricted access

Qianrong Qi, Yifan Yang, Kailin Wu and Qingzhen Xie

Recent studies revealed that TMEM16A is involved in several reproductive processes, including ovarian estrogen secretion and ovulation, sperm motility and acrosome reaction, fertilization and myometrium contraction. However, little is known about the expression and function of TMEM16A in embryo implantation and decidualization. In this study, we focused on the expression and regulation of TMEM16A in mouse uterus during early pregnancy. We found that TMEM16A is upregulated in uterine endometrium in response to embryo implantation and decidualization. Progesterone treatment could induce TMEM16A expression in endometrial stromal cells through progesterone receptor/c-Myc pathway, which is blocked by progesterone receptor antagonist or the inhibitor of c-Myc signaling pathway. Inhibition of TMEM16A by small molecule inhibitor (T16Ainh-A01) resulted in impaired embryo implantation and decidualization in mice. Treatment with either specific siRNA of Tmem16a or T16Ainh-A01 inhibited the decidualization and proliferation of mouse endometrial stromal cells. In conclusion, our results revealed that TMEM16A is involved in embryo implantation and decidualization in mice, compromised function of TMEM16A may lead to impaired embryo implantation and decidualization.