The first major advancements in endocrinologic knowledge came from studies pertaining to the testis. Aristotle1 recognized that the absence of the testis is responsible for the changes observed in castrate animals and man. In 1849 Berthold2 concluded that the testis produces an internal secretion, since capons with an implanted testis have comb growth and other characteristics of the cock. Thereafter, the study of testicular function lagged behind that of other ductless glands until, as a result of intensive study3 during the last decade, the status of androgenic substances shifted abruptly from that of relatively unknown materials to that of highly active crystalline compounds that can be prepared synthetically and are available for therapeutic use.
The androgens of chief interest in therapeusis are testosterone, a substance isolated from testis tissue (of the bull4), and androsterone and dehydroisoandrosterone, which are excreted in human urine.5 Clinically, testosterone is