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The concept of the onychodermis (specialized nail mesenchyme): an embryological assessment and a comparative analysis with the hair follicle
Author(s) -
Sellheyer Klaus,
Nelson Paula
Publication year - 2013
Publication title -
journal of cutaneous pathology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.597
H-Index - 75
eISSN - 1600-0560
pISSN - 0303-6987
DOI - 10.1111/cup.12101
Subject(s) - mesenchyme , nail (fastener) , pathology , hair follicle , biology , mesenchymal stem cell , anatomy , cd34 , fetus , medicine , stem cell , microbiology and biotechnology , pregnancy , materials science , genetics , metallurgy
Background Recently, an intriguing concept was introduced into the literature that defines the area underlying the nail bed as a specific mesenchymal substructure unique to the nail organ. It has been termed onychodermis . The onychodermis expresses CD10 with remarkable specificity. Herein, we compare adult and fetal human hair follicles with fetal nail organs in an attempt to draw analogies for the mesenchyme associated with both adnexal structures. Methods We examined immunohistochemically samples from adult and fetal hair follicles for the expression of CD10 , CD34 and the mesenchymal stem cell marker nestin and compared the antigen profile with that of the fetal nail organ. Results The CD10 ‐positive/ CD34 ‐negative onychodermis is prominently visible at the end of the second trimester. A corresponding follicular structure was not identified, either in the adult or in the developing hair follicle. Nestin staining does not define the onychodermis. Conclusions The concept of the onychodermis is equally valid in the developing nail organ where it is also defined by its expression for CD10 . Its function may be related to the anchorage of the overlying nail bed but may also involve a more dynamic role in the induction of hard keratins in the latter, contributing to the formation of the nail plate.