ABSTRACT
Gonadotropins are commonly used for superovulation in human and animals to retrieve more oocyte and increase chance of pregnancy. Ovarian stimulation in assisted reproduction technology produces lower implantation rates per embryo transferred than natural and ovum donation cycles, suggesting suboptimal endometrial development due to the hormones used to recruit more oocytes. Due to the frequent use of gonadotropins in the treatment of infertility in successive periods, the aim of this study was to determine the endometrial changes in response to repeated ovarian stimulation. This experimental interventional study has done in research center of Hamadan university of medical sciences in 2012. NMIRI female mice six weeks old were used in this study and divided into 7 groups [5 each]. The mice in group 1, 2, 3 and 4 received 1, 2, 3 and 4 times pregnant mare serum gonadotropin [PMSG] and 48 hours later 7.5 IU human chorionic gonadotrophin [hCG] respectively. For each group were considered a control group which received on time gonadortropin injection. The mouses were killed 13-16 hours after hCG injection and middle part of uterine horn cut for histological study using Hematoxylin and Eosin staining. The parameters that studied were surface epithelium of endometrium, glandular epithelium, and endometrial height and axis of uterine gland. Our results showed that there are no significant differences in glandular epithelium, axis of glands and height of endometrium in experimental groups [P>0.05]. The height of surface epithelium showed significant increases after ovarian stimulation in experiment group [P0.03]. Our results showed that there are no significant differences in glandular epithelium, axis of glands, height of endometrium and height of surface epithelium between control groups and also it's experimental group [P>0.05]. Conclusion Changes in the height of surface epithelium could be one of the reasons for decrease implantation rates with repeated ovarian stimulation