Staining of Human Skin With RGB Trichrome Unveils a Proteoglycan-Enriched Zone in the Hair Dermal Sheath

The study highlights the use of RGB trichrome staining, a method combining picrosirius Red, fast Green, and alcian Blue, on human skin samples to enhance the visualization of skin structures. This staining technique provides clear differentiation between the epidermis and dermis and allows for detailed observation of dermal structures such as blood vessels, nerves, and glands. Specifically, in hair follicles, RGB staining revealed two distinct zones within the dermal sheath where proteoglycans are predominant, as indicated by the blue over red staining. These zones are the dermal papilla, known for its role in hair growth, and a newly identified area termed the proteoglycan-enriched belt (PEB). The function of the PEB is not yet understood and warrants further research. The study suggests that RGB staining could be a valuable tool for the objective quantification of collagen and the study of skin and hair follicle biology.