Segmental cell kinetics of the human anagen hair: a DNA-flow cytometric analysis

The cell kinetics of anagen scalp hair taken by punch biopsies from 70 healthy male volunteers were determined at nine different defined bulbar and follicular hair segments using microdissection and DNA-flow cytometry. The highest mean proliferative activity (S-phase) was measured within the lowermost bulbar segment (14.0%), but decreased to 7.6% at Auber's segment and to 5.9% at the follicle isthmus. Notably, the S-phase data of the upper follicular segments (subdermal 2.4%, infundibular 2.4%) were found to be similar to those of the epidermis (2.5%). This study supporting and supplementing former autoradiographic investigations on human hair matrix epithelium clearly demonstrates the main proliferative activity of the anagen hair follicle being localized in the bulbar segments below Auber's level. Moreover, the method described is well suited for studying the effects of agents influencing cell growth (e.g., hormones or drugs) on the cell kinetics of different anagen hair compartments.