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Hair shaft melanin components ��eumelanin or/and pheomelanin�� are a long-lived record of precise interactions of hair follicle pigmentary units. Follicular melanogenesis ��FM�� sequentially involves the following processes: melanin synthesis by follicular melanocytes, the transfer of melanin granules into cortical and medulla keratinocytes, and the formation of pigmented hair shafts. This process is regulated by an array of enzymes, structural proteins, regulatory proteins, transporters, receptors and their ligands at different developmental stages. FM is stringently coupled to the anagen stage of hair cycle. The melanocyte compartments in the upper hair follicle also provide a reservoir for the repigmentation of epidermis and, for the cyclic formation of new anagen hair bulbs.