HUMAN HAIR FOLLICLES 915 Table VII Adenyl Cyclase Activity of Growing Hair Follicles Subjects #KA #AD #KO Additions (• (m•moles/hr/mg wet wt tissue) Av. None (control) 68.8 64.8 68.0 67.2 4- Testosterone 68.8 40.0 76.0 61.6 4- 5a-dihydrotestosterone 28.8 16.0 52.0 32.3 4- Esterone 150.0 ... 141.5 145.8 The concentration of each hormone added was 50/•g/ml reagent mixture. As shown in Table VII, the particulate fraction obtained froxn scalp hair follicles no doubt possesses sex hormone dependent adenyl cyclase activity. A male sex hormone (if it is tissue active) inhibits the adenyl cyclase whereas a female hormone increases its activity. The inhibition of this enzyme by 5oz-dihydrotestosterone but not by testosterone suggests strongly that the former is the tissue-active male hormone in hair follicles. Thus, data presented in Table VII represent the enzymatic evidence for the hormonal control of hair follicle metabo- lism. * STUDIES ON THE STUMP-TAILED MACAQUE--MODEL SYSTEM FOR COMMON BALDNESS Montagna (6-8) discovered that some subhuman prixnates develop baldness, a condition long considered peculiar to the human scalp. Of particular interest are the stmnp-tailed xnacaque, orangutah, and chixn- panzee, many of whom reveal during maturation varying degrees of alopecia in a triangular area just above the eyebrows. Since the stump- tailed macaque is a more practical laboratory animal than the others, it was selected for these studies on common baldness. To understand the difference between the bald and the hairy scalp, one must understand the structure and distribution of hair follicles in the scalp. The "hairy" part contains mostly large, stout, terminal ariagert hairs while the bald region contains thin, small, veilus-type ariagert and telogen hairs (Fig. 6). A detailed trichograxn study on the scalp hair follicles of the stuxnp-tailed macaque revealed (36) that both the hairy and the bald scalp contained about the same number of hair *• Both dihydrotestosterone and esterone show no effect on cyclic AMP phosphodiesterase activities in the hair follicles (unpublished observation).

916 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS