The hair cycle on the human thigh and upper arm.

Hair follicle density, and definitive length, root status and rate of growth of hairs were determined for defined areas of the thigh and upper arm in 11 females and nine males aged 20-30 years. Hair follicle density did not differ between males and females. However, on the thigh the definitive length of hair was on average three times greater in males. This was attributable mainly to a longer duration of anagen (X 2 X 46), but also to a greater rate of growth (X 1 X 22). On the upper arm the hair was only 1 X 42 times longer and the duration of anagen only 1 X 27 times greater in males than in females. On the thigh the estimated average duration of anagen was 54 days in males and 22 days in females, with corresponding figures of 151 days and 84 days for the complete cycles. On the upper arms the duration of anagen was 28 days in males and 22 days in females, with corresponding figures of 108 and 106 days for the complete cycle. In females, oral contraceptives had no significant effects on any measurement.