ITT4 Intratesticular Hormonal Milieu in Man (ITT4)

The purpose of this research study is to determine how much male hormone, testosterone, is necessary to maintain sperm production in the testis. This knowledge will be used to help in the development of a safe male hormonal contraception. Specific Aims: 1. to determine if ketoconazole plus acyline will suppress intratesticular testosterone(ITT) to a greater degree than acyline alone. 2. to determine if dutasteride plus acyline will suppress intratesticular dihydrotestosterone (IT-DHT) to a greater degree than acyline alone. 3. to determine if anastrazole plus acyline will suppress intratesticular estradiol(IT-E2) to a greater degree than acyline alone.