Abstract: Objective To investigate the regulation of estradiol valerate on endometrial receptivity in mice with embryonic implantation dysfunction. Methods The female KM mice were randomized into negative control group,model group and estradiol valerate group ,with 33 mice for each group, to build embryo implantation dysfunction mouse model. Mice in estradiol valerate group were administrated by gastric perfusion of 0.2mg/kg estradiol valerate and mice in negative control group and model group was given by the same dose saline. Mice were sacrificed individually at 9∶00, 21:00 and 23∶00 in the 4th day after gestation, and uterus were taken out for detecting pinopode by scanning electron microscopy and the expression of MMP-9,TIMP-3,COX-2 and PGI₂ by immunohistochemistry. Results The pinopode of endometrium in negative control group was uniform distribution,significantly more prominent than processes on the surface of membrane,with almost same size and clear boundaries, which was the developing pinopode. The pinopode of endometrium in model group was reversible focal expression, with asynchronized development of pinopode, or the inconsistent size of pinopode. There were a large number processes in endometrium with inconsistent size, slightly lower than that in the negative control group:short and thin microvilli on the surface of processes also was the developing pinopode,slightly later development lagged behind than that in the negative control group on morphology. There was significant difference between the model group and negative control group by the expression of COX-2, PGI₂ and MMP-9 protein, protein of endometrial glandular epithelial cells and luminal epithelial cells (P<0.05), comparing with the negative control group, the expression of TIMP-3 protein in endometrial glandular epithelial cells and luminal epithelial cells had significant difference in the model group (P<0.01), valerate estradiol significantly increased the expression of COX-2, PGI2, TIMP-3 and MMP-9 protein in the endometrium (P<0.05). Conclusion Estradiol valerate could improve embryo implantation and it may works by indirectly promoting of pinopode formation in mice with embryonic implantation dysfunction, increasing of the expression of COX-2, PGI₂, TIMP-3 and MMP-9 in endometrium, and establishing endometrial receptivity, for improving embryo implantation dysfunction of mice.

Key words: Estradiol valerate, Implantation, Blastocyst, COX-2 and PGI₂, MMP-9 and TIMP-3, Pinopode