The tubal environment holds a strategic location with respect to the reproductive processes. Histological visualization and biochemical analysis have shown that both oviductal tissue activity and fluid constituents are influenced by the hormonal state of the female. Also, tubal epithelial synthetic activity appears to be affected by the proximal embryo. The functional importance of differential oviductal secretions is presently unclear. However, the techniques of in vitro fertilization, embryo transfer, and culture aid in defining minimal developmental requirements and effects of cyclic secretions on embryologic events.