Abstract

Implantation is a complex process by which the embryo attaches to the endometrium. The human endometrium becomes receptive to the embryo during the luteal phase of the menstrual cycle under the influence of steroid hormones and paracrine factors originating from endometrial cells and the embryo. Several paracrine factors influencing the implantation include leukemia inhibitory factor (LIF) and interleukin (IL)-11. Moreover, timely development of pinopodes, and expression of integrins and Hox genes in endometrium, and oocyte quality also determines the implantation outcome. Endometriosis is a common gynecologic disorder and estimated that 25 to 50% of infertile women have endometriosis. Although the mechanisms contributing to infertility are poorly understood, accumulating evidence suggests that altered folliculogenesis, sperm dysfunction, impaired fertilization, toxicity against early embryonic development, defective implantation, and poor oocyte quality with decreased ability to implant may be the contributing factors in some endometriosis patients.