| Backgroud:Blastocyst implantation is an important step in reproduction of humans and mammals, it is crucial for successful pregnancy, however, its mechanism has not been well cleared. This process can be mediated through trophoblastic cell which originated in trophectoderm; the blastocyst cavity surrounded it and the inner cell mass [1]. Trophoblast cells develop into invasive phenotype and invade endometrial after 10-15 h with mice blastocyst hatching, this process includes the blastocyst discriminate, adhere and invade endometrial epithelium and so on. At"nidation window phase", the success blastocyst implantation depends on circumstance of endometrial receptivity and synchronous development of invasive blastocyst, which is accurately regulated by the extremely complex multi-factor.Embryos were called as a "benign tumor" by some people, that is because there are many similarities in the process and the biological mechanism between embryonic trophoblast invading into endometrial and invasion and metastasis of tumor cells, [2] A great many people pay more attention to the function and mechanism of proto-oncogenes and anti-oncogenes during blastocyst implantation. Survivin, inhibitor of apoptosis proteins (IAP) family of a new member, is by far the smallest cloned IAP and locate in human chromosome 17 q25.3 with a total length of 14.7 kb, encoding 142 amino acids and 16.5 kD protein.Survivin is existed in mouse embryonic tissue and the majority of human malignant tumor tissues[3]. Survivin gene knock-out can lead to the death of mouse embryos of d4-5[4]. In short, Survivin is an essential tumor suppressor factor in the process of embryonic development. Therefore, we supposed that Survivin plays an important role in the process of inducing apoptosis of endometrial epithelial cells, decidual cells and trophoblast cell and promoting cell proliferation and forming blood vessel during embryo implantation. However, at home and abroad, Survivin expression in early pregnancy mice endometrial has no reported in the literature of related research topic.Objective: To investigate the expression of Survivin in mouse endometrium and its function during Blastocyst implantationMethods:1. Mouse endometrium in un-pregnant and pregnant mice on days 2, 3, 4, 5, 6, 7 of pregnancy were used to study. There are 7 groups, each group has 10 mice. Real-time fluorescent quantitative PCR (FQ-PCR) and immunohistoc- hemical techniques were applied to detect Survivin mRNA and protein expressions, respectively.2. Survivin antibody was injected into the horns of uterus in pregnant mice on day 4 of pregnancy and the number of implantation sites was recorded on day 8 of pregnancy.Results :1. The higher expressions of Survivin mRNA /β-actin mRNA were observed in pregnant mice compared with that in un-pregnant mice, with a steady increasing from day 2 to 7 of pregnancy and reaching the maximal level on day 6 of pregnancy.2. Immunohistochemical analysis showed that the expression of Survivin protein was same with the one of mRNA. Survivin protein extensive expressed in mouse endometrium, especially in the luminal epithelium and glandular epithelial cell membrane and the cytoplasm, as well as vascular endothelial cells and the nucleus of stromal cells.3. At 8:00 in the morning the polyclonal antibodies of Survivin were injected into uterine horn of pregnant mice on days 4 of pregnancy and the number of implantation sites was recorded on day 8, the results showed that the number of Survivin antibody injection group significantly decreased, comparing with saline injection (p <0.05).Conclusion: Expression of survivin in mouse endometrium during early pregnancy indicates that survivin might inhibit apoptosis of decidual cells, coordinating further decidualization of endometrium and invasion of trophoblastic cells. The result of Survivin antibody injection in uteri horn showed that the number of implantation was significantly decreased. These results suggested that Survivin might participate in the process of blastocyst implantation in mice.
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