The  development  and  secretory  activity  of  the sebaceous gland are unquestionably under androgen control. The testes synthesize testosterone, the main circulating  androgen,  and  A5-androstenediol.  The adrenal gland is  the main source of dehydroepiandrosterone (DHA) and dehydroepiandrosterone sulphate (DHAS), which is quantitatively the major circulating  adrenal androgen.

The adrenals  also  produce androstenedione   and  A5-androstenediol,  the  latter being  an  important circulating androgen in  women. The ovary  is capable of synthesizing  testosterone, androstenedione and DHA. Some hormones are transported in a  bound form: for example, testosterone is carried by sex hormone binding globulin (SHBG). A high level of SHBG signifies a lower level of the free hormone. (In functional  terms,  free hormones  are biologically  more  active.) With increasing sophistication more free hormones can be measured, including free dihydrotestosterone (DHT).

 

  The effect  of  some of these  hormones  on  the sebaceous  glands  was investigated by Pochi  and Strauss, who administered large amounts of oestrogens to adult  males to reduce sebaceous gland activity to prepubertal   levels  and  then   injected  various androgens.  This  and  many other studies have  confirmed the  androgen  dependency  of the sebaceous glands. sebaceous  glands could use adrenal  androgens to synthesize  more potent androgens. The  adrenal is more active in androgen metabolism earlier in life than the  testes,  and so adrenal  androgens may play an important  role  in the initiation  of sebaceous  gland activity; they may also be more important in juvenile acne.

 

  Human skin  is a collection of androgen-responsive tissues, i.e.  hair follicles,  sebaceous  glands,  sweat glands, epidermis and  dermis.  This  complexity of tissue has made difficult the interpretation of results derived from incubation of whole skin.