Two- and three-dimensional observations of human terminal and vellus hair follicles.

Extracted human terminal and vellus hair follicles were prepared by EDTA and examined by light and electron microscopes. These samples were morphologically well preserved and enabled us to observe 3-dimensional (3-D) views of the outer surfaces of hair follicles. Interestingly, the bulge areas of terminal and vellus hair follicles showed several morphological variations, such as knob-like swellings and villous projections, independent of hair cycle. Moreover, skirt-like structures were furnished in the small vellus hair follicles independent of hair cycle, but not terminal and large vellus hair follicles. These morphological variations of human hair follicles were confirmed to genuinely represent 3-D views by means of the conventional transverse and vertical sections of the human skin.