The upper dermal sheath has a potential to regenerate the hair in the rat follicular epidermis

The study from 1996 demonstrated that the upper dermal sheath of a rat vibrissa follicle had the potential to regenerate hair, contrary to previous beliefs. When the upper halves of the follicles were implanted under the kidney capsule for 8 weeks, pelage-type hairs were produced. Monoclonal antibody analysis revealed the formation of small hair bulbs due to interactions between upper dermal sheath cells and follicular basal cells. These new bulbs formed at the amputated end and upper region of the follicles, but not near the bulge area where stem cells are located. The study suggested that while the hair-inducing ability of the upper dermal sheath was weaker compared to lower dermal compartments, it was still sufficient to induce hair production under specific conditions.