Successful implantation involves a complex interaction between the endometrium and the embryo. It is well known that several neuropeptides are expressed in the endometrium and placenta during embryonal implantation, suggesting an important role as chemical mediators of the feto-maternal relationship. Ghrelin has recently been identified as the endogenous ligand for the GH secretagogue receptor. Ghrelin is a peptide hormone with many physiological functions, and its expression in the human placenta has been reported. To investigate the involvement of ghrelin in embryonal implantation, we assessed the spatio-temporal expression pattern of ghrelin and its receptor in the human endometrium and placenta through the normal menstrual cycle and in early pregnancy. We also examined the effect of ghrelin on the decidualization of endometrial stromal cells (ESC). Weak expression of ghrelin mRNA was detected in the nonpregnant endometrium, and it was dramatically increased in the decidualized endometrium. A GH secretagogue receptor mRNA was detected in the endometrium throughout the normal menstrual cycle and in early pregnancy, but not in the first trimester placenta. Immunohistochemical analysis using an antighrelin antibody revealed strong signals in decidual cells and extravillous trophoblast cells. Coculture with first trimester placenta up-regulated ghrelin mRNA expression by primary cultured ESC, although sex steroids and 8-bromo-cAMP had no effect. In addition, ghrelin enhanced the decidualization of ESC induced by 8-bromo-cAMP (8-Br-cAMP) in vitro. Thus, ghrelin is a novel paracrine/autocrine factor that is involved in cross-talk between the endometrium and embryo during embryonal implantation.

Decidualisation of endometrial stromal cells (ESC) is a prerequisite for the implantation of human embryos. Identification of genes that are upregulated or downregulated during decidualisation could lead to a better understanding of the molecular mechanisms involved in this process. In the present study, we examined differences in gene expression between decidualised and non-decidualised cells using microarray analysis and found that Factor XII (FXII) gene expression was upregulated during decidualisation. Furthermore, we also examined the expression of FXII by human ESC before and during pregnancy, as well as its expression by cells that had undergone decidualisation in vitro. Weak expression of FXII mRNA was detected in the non-pregnant endometrium that increased gradually from the proliferative to the secretory endometrium. During pregnancy, FXII mRNA expression was markedly increased in decidualised endometrium. When sex steroids (200 pg mL(-1) of 17beta-oestradiol and 100 ng mL(-1) of progesterone) were used to induce in vitro decidualisation of ESC, the expression of FXII mRNA increased by approximately 25.3-fold compared with that in non-decidualised ESC. Using western blotting, we confirmed the presence of FXII protein (80 kDa) in ESC after in vitro decidualisation. Increased expression of FXII in ESC during decidualisation suggests that the kallikrein-kininogen-kinin system may be activated during the implantation of human embryos.

These results suggest that cAMP-induced region of the human dPRL promoter resides between -1862 and -1856, -1703 and -1697, -310 and -285, and that the sequences between -1862 and -1856, -1703 and -1697 of the promoter display E + P-induced promoter activity. Furthermore, the current study indicates that E + P or cAMP cooperatively regulate the dPRL gene transcription through some transcriptional factors such as C/EBP, CREB, and other cofactor(s), and that some repressor(s) or corepressor(s) may be involved in the C/EBP-binding site of the human dPRL promoter.

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Purpose Early rescue intracytoplasmic sperm injection (ICSI) is often performed in cases in which not even a single oocyte has extruded a second polar body 6 h after insemination. We evaluated the usefulness of expanding the indications of early rescue ICSI to cases in which <80% of oocytes have extruded second polar bodies 6 h after insemination. Methods Early rescue ICSI was performed on oocytes that were denuded 2.5 h post‐insemination and whose extrusion of the second polar bodies had been examined 6 h post‐insemination with a PolScope. Results In vitro fertilization was performed on 24 496 oocytes of 4944 cycles, and 1438 cycles had <80% rate of the second polar body extrusion. Rescue ICSI was performed on 3933 oocytes. Three pronuclei (3PN) incidence of rescue ICSI was 3.0% in oocytes with ≥50% rate of the second polar body extrusion. With respect to the second polar body extrusion rate, no differences were observed in normal fertilization, blastocyst development, implantation, miscarriage, or live birth rates for rescue ICSI. Conclusion By expanding the indications of early rescue ICSI using the PolScope to cases in which <80% of oocytes have extruded the second polar bodies, many fertilized oocytes can be obtained without considerably increasing the 3PN rate.