This is a nine-month research study examining the effects on androgen treatment on sperm production in healthy men. There are three phase to the study, a 2-month screening phase, 4-month treatment and 3-month follow-up. In this study, the investigators aim to define a quantitative relationship between intra-testicular testosterone (IT-T) and spermatogenesis in man. Hormone levels will be measured in a small amount of testicular fluid at the beginning and end of treatment and sperm concentration will be measured.