Growth factors in reproduction.

The changes that occur in the female reproductive tract during the menstrual cycle and in early pregnancy, in preparation for embryo implantation and subsequent placental and fetal development, have long attracted the interest of reproductive biologists. The early embryo expresses growth factors and growth factor receptors that are, in general, temporally expressed. In addition, the oviduct and uterine endometrium also synthesize growth factors and cytokines, and the developing embryo finds itself in a growth-factor-rich milieu during early development. The autocrine, juxtracrine, and paracrine actions of these factors in the development of the early embryo and of the maternal reproductive tract are just beginning to be appreciated, as are their potential roles in cellular proliferation and cell-cell communication within the developing embryo, in the reproductive tract, and at the maternal-trophoblast interface. When detailed mechanisms underlying these interactions are fully understood, it is anticipated that therapies will be rationally designed to treat reproductive disorders associated with abnormal embryonic development and poor placentation.