Men involved in the study will have detailed evaluations that involve overnight stays in the hospital and frequent blood sampling. The men in the study will also be receiving medications that affect the levels of various hormones in the body. This will allow the researchers to learn how various hormones influence each other. Men that participate in the study will receive medical evaluations and monetary compensation. Information gathered from this study will help in the development of new treatments for infertility and potentially new hormonal forms of contraception.