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The nail dermis: from microanatomy to constitutive modelling
Author(s) -
Perrin Christophe
Publication year - 2015
Publication title -
histopathology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.626
H-Index - 124
eISSN - 1365-2559
pISSN - 0309-0167
DOI - 10.1111/his.12608
Subject(s) - mesenchyme , dermis , nail (fastener) , anatomy , pathology , connective tissue , biology , reticular dermis , medicine , mesenchymal stem cell , materials science , metallurgy
Aims The nail mesenchyme, as ligamentous connective tissue, is classically described as a single compartment. Some authors have even suggested the concept of the nail as a musculoskeletal appendage. Recent studies conducted on supernumerary digits surgically removed for polydactyly or on the developing nail organ have introduced into the literature a new concept: the onychodermis and its onychofibroblasts that are CD 10‐positive/ CD 34‐negative. The aim of this study was to explore the nail mesenchyme more comprehensively. Methods and results A series of 10 normal adult nail units were examined with a combination of morphological and immunohistochemical analysis. This study demonstrates that the nail mesenchyme has two distinct compartments, with a complex microanatomy of matrical dermis and its hypoderm. The matrical dermis is a relatively independent substructure, and comprises two parts: a thin papillary dermis, and a relatively thick reticular dermis. The matrical hypoderm corresponds to a cushion‐like layer of adipose tissue, which distally intermingles with an area of loose connective tissue. The nail bed dermis comprises a single, relatively homogeneous compartment. Conclusion The matrical nail mesenchyme is a modified dermis. The concept of onychodermis is not applicable in the normal adult nail. Underrecognized non‐pathological structures may pose diagnostic problems. The chameleon matrical hypoderm is one such structure.