The Concept of the Onychodermis: An Embryological Assessment and Comparative Analysis with the Hair Follicle

The study introduced the concept of the onychodermis, a specialized mesenchymal substructure unique to the nail organ, characterized by its expression of CD10. Researchers compared the antigen profiles of adult and fetal hair follicles with fetal nail organs, finding that the CD10-positive/CD34-negative onychodermis was visible by the end of the second trimester, with no corresponding structure in hair follicles. The onychodermis may play a role in anchoring the nail bed and inducing hard keratins, contributing to nail plate formation.