Dermal-epidermal interactions

The study established that the dermal papilla, a stable population of specialized fibroblasts, interacts with the epidermis to ensure follicle development and continues to influence the hair cycle by undergoing cyclic changes in size and activity. The lower follicle dermis retains embryonic characteristics, re-enacting its inductive influence to regulate morphogenetic changes and determine hair fiber characteristics. The papilla provides factors that stimulate epidermal proliferation, initiating and sustaining anagen and follicle morphogenesis. Coculture experiments showed that papilla cells enhance epidermal cell attachment and proliferation, suggesting that the hair cycle depends on an intrapapillary cycle of events and that the dermal component may mediate systemic factors influencing follicle behavior.