The implantation process involves complex and synchronized molecular and cellular events between the uterus and the implanting embryo

Background: Acceptance of uterus and reaction between endometrium and embryo has an important role for implantation. Muc1, an integral membrane mucin, is expressed on the apical surface of uterine epithelial cells and could have effects on its receptivity. Objective: The aim of this study was to evaluate the changes in Muc1 expression of gravid mouse endometrium with and without hyperstimulation before implantation. Materials and Methods: Adult female NMRI mice were divided into control and experimental groups. Experimental group superovulated using an intraperitoneal injection of Pregnant Mare’s Serum Gonadotrophin (PMSG) followed 48 hours later by another injection of Human Chorionic Gonadotropic hormone (HCG). The female mice have mated with normal male mice. All control and hyperstimulated groups subdivided into six groups. After mating, female mice were examined by vaginal plaque as day of zero and in 0-5 days after copulation, they were sacrificed by cervical dislocation. Then the middle 1/3 parts of their uterine horns were obtained and stained by immunohistochemicaly technique for Muc-1 detection. Results: Our results showed that in the control and hyperstimulated groups, the Muc1 expression is markedly reduced in the luminal uterus epithelium at the time of implantation. Furthermore, luminal and glandular uterus epithelium did not exhibit the same decrease in Muc1 expression during the receptive phase. Conclusion: Ovarian hyperstimulation didn’t alter the Muc1 expression markedly in surface and glandular epithelium of endometrium, which could affect on its receptivity.