c-Myc expression in human anagen hair follicles

The hair follicle represents a very am-active organ system for studying the precise balance between cell proliferation, growth, differentiation, and d eath of cells, because it periodically and regularly regenerates, retaining its morphogenetic signals throughout its life, One of the most intriguing oncogenes which is able to induce both cell growth and apoptosis, depending upon the environmental conditions, is c-myc. The aim of the present study was to investigate its presence and localization in human hair follicles by immunohistochemistry and immunofluorescence. Our observations demonstrated the consistent presence of two clusters of c-Myc-expressing cells in anage n follicles, located in two annular regions of the inner root sheath, at th e border between cells characterized by putative trichohyalin granules and cells which are keratinized. The lower group belongs to Henle's layer, whil e the upper group belongs to Huxley's layer, c-Myc oncoprotein seems to fav our apoptosis/differentiation and may be a marker for terminal differentiat ion of trichocytes, at least in the inner root sheath. Our findings agree w ith the interpretation that the complex morphology of the hair follicle ref lects its complex function; the extrusion of a highly organized multicellul ar structure, the hair shaft, driven by another highly organized multicellu lar structure, the inner root sheath.