It has been known for some time that certain types of cells, including those in reproduction tissues, produce substances that act by autocrine and paracrine means to control cellular functions, including promotion and inhibition of cell growth. This volume is based on a symposium held under the sponsorship of the World Health Organization to review the many newly recognised growth factors controlling physiological functions of the reproductive tract. The contributions presented here offer new and expanded insights into the functioning of the reproductive tract, examining many basic physiological and molecular mechanisms with potential in the development of new approaches to fertility regulation. Promising areas for further research are identified, and new systems for in vitro study of growth factors discussed.