The broad objectives of this 3-year project are to identify pregnancy-associated proteins in the primate endometrium and to obtain basic information about such proteins with respect to hormonal control of their synthesis, their tissue-, and species-specificity and their biochemical nature, to isolate them in pure form, to develop a sensitive assay for their determination in tissues and body fluids, and, lastly, to develop an animal model to study their biologic roles and potential for fertility control. We have, during the two project years, identified two chemically similar, pregnancy-associated antigenic proteins, termed antigens A and B, in the human endometrium. These antigens have been partially-purified and their properties studied. Methods are being developed to further purify and quantitate the two antigens, also we are exploring whether or not a baboon can be used as a non-human primate model to assess the potential use of the two antigens for fertility control or for evaluation of progestins and their effect on uterus. Preliminary studies have indicated the presence of at least one pregnancy-associated antigenic protein in the baboon endometrium. The relationship of this antigen to the human antigens A and B is being studied.