Perifollicular clear space under skirt-like epithelial structure of human small vellus hair follicle

Abstract

Human hair follicles, especially small vellus hair follicles, showed characteristic structures as follows: (I) small vellus hair follicles were surrounded with skirt-like epithelial structures or perifollicular connective tissue capsule; (II) perifollicular clear space was present between the outer root sheath and skirt-like structure, or the outer root sheath and perifollicular connective tissue capsule; (III) perifollicular clear space was filled with a loose, alcian blue positive mucinous substance and elongated fibroblasts and mast cells; (IV) perifollicular nerve endings were attached to the follicular wall in a palisading arrangement within the clear space under the skirt; (V) perifollicular nerve end organs and connective tissue capsule were positively immunostained for CD34 and protein gene product 9.5 (PGP9.5). These specialized structures of human small vellus hair follicles seem to correspond to the blood sinus of the sinus hair follicles, where similar structural elements were found.