The ultrastructure of the transition zone between specialized cells ("Flügelzellen") of Huxley's layer of the inner root sheath and cells of the outer root sheath of the human hair follicle.

We studied biopsy specimens taken from the scalp of four normal volunteers by transmission electron microscopy (TEM). At the suprabulbous level of the follicle, where the cells of Henle's layer are fully keratinized but the cells of Huxley's layer are not, the cytoplasmic processes of Huxley's layer ("Flügelzellen") reach the cells of the outer root sheath through the keratinized cylinder of Henle's layer. This junction between the outer root sheath cells and the "Flügelzellen" has not been previously characterized ultrastructurally. It is peculiar in its total lack of desmosomes, and it may have the features of a gap junction. The function of this structure and its possible role in hair growth is unknown. It may be related to nutrition, differentiation, or both.