Three-dimensional demonstration of melanocyte distribution of human hair follicles: special reference to the bulge area.

Melanocytes of human hair follicles were histochemically and immunohistochemically examined in two and three dimensions. EDTA-treated extracted anagen vellus and intermediate hair follicles showed that monoclonal murine antibody (MoAb) NKI/ beteb-reactive melanocytes were distributed from the infundibulum to the bulb. Melanocytes of the infundibulum and bulb were larger and more strongly stained with MoAb NKI/beteb than those of the middle portion below the sebaceous gland. Latter melanocytes showed less dendricity. Dendritic melanocytes were exclusively observed in the bulb as well as the bulge area of vellus and intermediate hair follicles, where they were variably melanized. In longitudinal and transverse sections of adult human scalp some keratinocytes of the outer root sheath of the bulge area were melanized compared to other parts. This phenomenon was independent of the hair cycle. These findings may be characteristic of bulge melanocytes and/or keratinocytes.