This study was undertaken to determine the effect of estradiol and progesterone on the synthesis of oviduct-specific proteins and to determine if there were changes in the synthesis of these proteins in different regions of the oviduct. Ovariectomized females were either untreated, treated with estradiol for 7 or 14 days, or primed with estradiol for 14 days and then treated with estradiol plus progesterone or progesterone alone for either 7 or 14 days. Oviducts were incubated in the presence of labeled methionine or glucosamine for 24 h at 37 C, and the culture medium was then analyzed by one- and two-dimensional (2-D) polyacrylamide gel electrophoresis, followed by fluorography. A family of macromolecules [mol wt (Mr), 100,000-130,000] was only present in the animals treated with estradiol for 7 or 14 days. 2-D analysis demonstrated that two proteins, one basic and one acidic, were the major estradiol-responsive proteins in the 100,000-130,000 Mr region. In addition, an acidic protein in this region increased in intensity with estradiol treatment. All three proteins incorporated methionine and glucosamine. Since a steroid-responsive gradient is known to exist in the oviduct, oviducts were divided into fimbria, ampulla, and isthmic regions and cultured separately. 2-D analysis of the medium indicated that the ampulla synthesized both the acidic (Mr, 100,000-120,000) and basic (Mr, 120,000-130,000) proteins, whereas the acidic protein was dominant in the fimbria and the basic protein was dominant in the isthmus. Another acidic protein (Mr, 110,000) was only present in the fimbria and ampulla. This study clearly demonstrates that the estradiol-treated baboon oviduct synthesizes several proteins that were not detectable in the ovariectomized or progesterone-treated animal. Also, the different regions of the oviduct have different synthetic capabilities for these proteins. The electrophoretic characteristics of these proteins are similar to those we have observed at midcycle in the intact baboon and human oviduct.