Several growth factors and cytokines appear to be involved in the process of implantation. Stem cell factor and its receptor c-kit regulate the progression and survival of germ cells and play an important role in follicular development. It is present in the follicular fluid however little information was available on the role of stem cell factor and its receptor in the process of blastocyst implantation. It was not until Mitsunari examined the expression of stem cell factor and its receptor in mouse embryos and in the stromal and epithelial cells of the uterine endometrium by reverse transcription -polymerase chain reaction . He illustrated that stem cell factor derived from endometrial cells and the implanting embryo exerts paracrine and autocrine action on the process of implantation by stimulating trophoblast outgrowth through its receptor c-kit (6).