En 1680-6433 2008-2177 The ovarian stimulation effects on Muc1 expression of the mouse endometrium before implantation 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. 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. Endometrium Muc1 expression Ovarian stimulation. Endometrium Muc1 expression Ovarian stimulation. 157 162 Marzieh Panahi marzpanah@yahoo.com No Azam Soleimani No Mahmoud No Abdolrahman Abdolrahman Dezfoolian No