Ultrastructural characteristics and mucin-1 expression of secretory endometrium of women with unexplained infertility

Inefficiency in implantation is one of the most important factors limiting the success rate of assisted reproduction in the patients with unexplained infertility. It is known that there are many molecular and structural indicators that affects on endometrial receptivity, which cause implantation failure. This study aims to investigate the role of endometrium during the period of implantation window in fertile women and infertile women with unexplained infertility by comparing morphological characteristics of endometrial tissues by light and electron microscopic examinations and immunohistochemically expression of MUC-1, which has an important role on implantation and biochemical levels evaluate the role of the results in success of implantation rate. In the present study, work and control groups were composed of 18 patients with unexplained infertility who applied to Çukurova University Faculty of Medicine Obstetrics and Gynecology Department Assisted Reproductive Techniques Unit and 18 patients with various gynecological complaints who applied to Çukurova University Faculty of Medicine Obstetrics and Gynecology Department, respectively. We performed endometrial biopsy to all patients on the 5th, 6th and 7th days after ovulation. Some part of endometrial tissue samples were prepared according to the method of light microscope, while the other parts were prepared according to the method of electron microscope. Hematoxylin-Eosin staining and immunohistochemical methods for determination of the MUC-1 were applied to the tissues for light microscopic examination. Serum hormone levels were also identified by taking blood samples on the 2nd day of menstrual cycle and on the biopsy day. Serum FSH, LH, TSH, estrogen, progesterone and testosterone levels were not significantly different between the two groups, but higher prolactin levels were detected in the infertile group. As a result of structural evaluation, it was observed that endometrial surface epithelium includes locally pseudostratified and squamous epithelial patches and the microvilli rich cells were very common, pinopod and vesiculated cells were considerably reduced, pinopod development was inefficient, in the simple columnar epithelium and intraepithelial lymphocytes were increased frequently between the epithelial cells in infertile group compared to fertile group. It was observed that developmental retardation of endometrial glands and mitosis continued in gland epithelial cells in infertile group compared to fertile group. It was determined that MUC-1 immunoreactivity was not significantly different between the two groups. It was concluded that structural differences on the surface and gland epithelium of endometrium in infertile patients might be caused from insufficient responses to steroid hormones of these cells and these differences can affect implantation of blastocyst to endometrium.