The P-50 Special Population Research Center described in this proposal is made up of co-investigators from the Center for Biomedical Research of the Population Council. The research conducted in the coming year will cover the following board areas of overlapping interest. We will determine the mechanism by which LHRH inhibits androgen action and study the androgen receptor with photoaffinity labeling technology. This will permit a more definitive study of inherited defects of the androgen receptor. A study of protein synthesis in Sertoli cells will be conducted to define unique markers of seminiferous tubular function in addition to androgen binding protein, which can be used to monitor the pathophysiology of the testis. These latter studies will be possible because of our ability to grow individual cell types from the testis in serum-free medium. This technology also permits an evaluation of how myoid and Sertoli cells interact to form the primitive seminiferous tubular epithelium. The specificity of the sperm receptor on zona pellucida will be evaluated using newly developed immunological and sperm binding assay. This will permit us to determine which of the zona-specific proteins comprise the sperm receptor in various species. The origin of the sperm receptor in the ovary can then be determined.