ABSTRACT
Background: the opening and closing of the implantation window is important for successful pregnancy in eutherians. The recent study demonstrated that the window of uterine receptivity was prepared by the sole action of progesterone in mice, but the mechanism to close the window remained to be elucidated
Methods: the pregnant mice were ovariectomized on the evening on the third day of pregnancy with a single injection of medroxyprogesterone acetate to induce delayed implantation [DI]. Several treatments were applied to DI mice. The uterine receptivity after treatment was assessed by examining cell proliferation in the uterine luminal epithelium [LE]. The gene expressions in the endometrium were investigated by RNA-seq. The p<0.05 was considered significant
Results: cell proliferation in the LE ceased only when the window of implantation was open. Estrogen [E2] stimulated cell proliferation in the LE rendered the uterus refractory. The high throughput gene expression analysis by RNA-Seq showed that the insulin-like growth factor 1 [IGF1] pathway was the candidate to close the implantation window under E2. In vivo administration of IGF1 to delayed implantation mice resulted in proliferation in the LE cells
Conclusion: this study demonstrated that the window of uterine receptivity was closed by E2, which was mediated by the IGF1 pathway
ABSTRACT
Mouse and vole embryos were allogeneically and xenogeneically transferred into pseudopregnant CD.1 and immunodeficient (seid)female mice,and we investigated the distribution of uterine leucocytes cells in the implantation sites on days 5,6,and 7 of pregnancy. Maerophages were evenly distributed in the endometrium on days 5-7.Neutrophils were rarely seen on days 5-7,but lymphocytes were found throughout the endometrium,often in groups associated with glands or the luminal epithelium.The number of uNK cells increased markedly at the mesometrial uriangle and the outer decidual area in the CD-1 uteri containing vole embryos;by contrast,seid uteri having vole embryos showed almost the same number as those having mouse embryos.Mast cells were present in large numbers at the myometrium,but rarely in the decidua in all types of pregnant uteri.Cells at the myometrium were more numerous in xenogeneic than in allogeneic transfer.Maay mast cells appeared in the inner decidua where xenogeneically transferred vole embryos were dead and aborted.These results suggest the possibility that uterine leucocytes mediate various immunological events in the mouse-vole interspesific pregnancies.