title: Is the eccrine gland an integral, functionally important component of the human scalp pilosebaceous unit?
abstract: The pilosebaceous unit (PSU) and the eccrine sweat gland (ESG) are classically described as completely independent skin appendages. However, careful inspection of scalp follicular units reveals that the secretory segment of the ESG spatially approximates the hair follicle in a position below the sebaceous gland and the insertion of the arrector pili muscle. Therefore, we propose here that, contrary to conventional wisdom, the PSU and the ESG should not be viewed in isolation, and may form instead, along with the arrector pili muscle and the apocrine gland (where present),one functional unit. For this, we suggest the more inclusive term of 'Hair Cluster' (HC). If confirmed, e.g. by 3D imaging techniques, the novel concept of a functional HC, whose individual components may communicate via secreted molecules and may share selected progenitor cell populations for HC repair/regeneration, has major physiological and pathological implications, which are briefly discussed.
authors.affiliation: Department of Pathology, University General Hospital, and Murcia University, Murcia, Spain.
authors.forename: Enrique
authors.initials: E
authors.lastname: Poblet
authors.affiliation: Mediteknia Dermatology Clinic and Medical Pathology Group, University of Las Palmas Gran Canaria, Canary Islands, Spain.
authors.forename: Francisco
authors.initials: F
authors.lastname: Jiménez-Acosta
authors.affiliation: Centre for Dermatology Research, Institute of Inflammation and Repair, University of Manchester, Manchester, UK.
authors.forename: Jonathan A
authors.initials: JA
authors.lastname: Hardman
authors.affiliation: Department of Dermatology, University General Hospital, Albacete, Spain.
authors.forename: Eduardo
authors.initials: E
authors.lastname: Escario
authors.affiliation: Centre for Dermatology Research, Institute of Inflammation and Repair, University of Manchester, Manchester, UK.|Department of Dermatology, University of Münster, Münster, Germany.
authors.forename: Ralf
authors.initials: R
authors.lastname: Paus
mesh_terms: D001050:Apocrine Glands / Q000033:anatomy & histology; D004439:Eccrine Glands / Q000033:anatomy & histology*; D018859:Hair Follicle / Q000033:anatomy & histology*; D006801:Humans; D009130:Muscle, Smooth / Q000033:anatomy & histology; D012535:Scalp / Q000033:anatomy & histology* / Q000502:physiology
keywords: eccrine sweat gland; hair follicle