Introductory remarks. General review of biological action. Gradients of influence. Sources, inactivation and excretion.

Introductory Remarks

THE term androgen is used here as a collective title for compounds which resemble testosterone in biological action. The chief function of these hormones is to stimulate the development and activity of the accessory male reproductive organs. On the general dimensions of the body androgens have little effect, the smaller size of the female in mankind and in many other mammals being due to the action of oestrogen rather than to a deficiency of androgen. On the skeleton and general conformation of the body the androgens appear to exercise some influence, as seen, for example, in pathological cases of virilism in women, a condition which is accompanied by an excessive excretion of androgen in the urine. When this disease affects young girls the shape of the body tends in time to become masculine in character; whereas with defective gonadal development in young males the contours of the body may become distinctly feminine, the hips being broad compared with the shoulders. The falsetto voice and hairless face of the eunuch who has been castrated in childhood may be attributed also to a deficiency of androgen; for the testis is the chief though not the only source of this kind of hormone. The distribution of hair on the body in men, the extent of the facial sinuses, and the many curious sexual adornments and peculiarities which the males of different species acquire, especially in the mating and breeding season, also depend for their appearance and maintenance on an adequate supply of androgen. The crest of the newt, the cock's comb, the rugose and swollen clasping digits of the male frog, and the bright coloration of some fishes in the breeding season are examples. At present it will be unnecessary to discuss these curiosities at length, and attention will be concentrated on the more constant and vital activities of the androgens in mammals, including man.