title: The presence and localization of onychodermis (specialized nail mesenchyme) containing onychofibroblasts in the nail unit: a morphological and immunohistochemical study.
abstract: OBJECTIVE
  Due to its limited availability there has been very little research on the mesenchyme of the nail unit. Recently, we discovered specialized mesenchymal cells beneath the nail matrix and proposed to call them onychofibroblasts. The purpose of this study was to further delineate more precisely by histology and immunohistochemistry the specialized nail mesenchyme.
  
  
  RESULTS
  Thirty supernumerary digits were obtained during operations to correct polydactyly. Longitudinal and transverse sections were obtained from formalin-fixed paraffin-embedded blocks. In sections stained with haematoxylin and eosin, a mesenchymal area that showed much more cellularity and less eosinophilic, loose connective tissue was identified beneath the nail matrix and nail bed. Using Alcian blue staining, mucin was detected in this mesenchymal area below the nail matrix and nail bed. Immnunohistochemically, CD10 and versican were expressed strongly in the mesenchyme containing onychofibroblasts under the nail matrix and nail bed.
  
  
  CONCLUSIONS
  These results demonstrate the presence and localization of a specialized nail mesenchyme containing onychofibroblasts in a well-defined area beneath the nail matrix and nail bed. Thus, we propose the term onychodermis for this specialized nail mesenchyme that is histologically and immunohistochemically distinct from the dermis of other parts of the nail unit.
authors.affiliation: Departmentsof Dermatology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, South Korea. dylee@skku.edu
authors.forename: Dong-Youn
authors.initials: DY
authors.lastname: Lee
authors.forename: Ji-Hye
authors.initials: JH
authors.lastname: Park
authors.forename: Hyun-Tae
authors.initials: HT
authors.lastname: Shin
authors.forename: Jun-Mo
authors.initials: JM
authors.lastname: Yang
authors.forename: Kee-Taek
authors.initials: KT
authors.lastname: Jang
authors.forename: Ghee Young
authors.initials: GY
authors.lastname: Kwon
authors.forename: Kyung-Hoon
authors.initials: KH
authors.lastname: Lee
authors.forename: Jong Sup
authors.initials: JS
authors.lastname: Shim
mesh_terms: D015415:Biomarkers / Q000378:metabolism; D002675:Child, Preschool; D005347:Fibroblasts / Q000166:cytology* / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry; D007223:Infant; D008648:Mesoderm / Q000166:cytology* / Q000378:metabolism; D009077:Mucins / Q000378:metabolism; D009262:Nails / Q000166:cytology* / Q000378:metabolism; D017689:Polydactyly / Q000601:surgery
chemical_list: D015415:Biomarkers; D009077:Mucins