Hair-Raising Mysteries of the Inner Root Sheath: Unearthing Treasures in Bald Spots
June 2025
Studysummary This review suggests that the inner root sheath of human hair follicles may have broader regulatory roles beyond structural support, potentially impacting processes like folliculogenesis, anagen phase regulation, and immunomodulation. Our plain-language summary of this paper — not a Tressless recommendation.
The review re-evaluates the role of the inner root sheath (IRS) in human hair follicles, traditionally seen as a structural component. It suggests that the IRS has broader functions, including involvement in signaling processes that affect folliculogenesis, anagen phase regulation, cell differentiation, immunomodulation, and keratinization. This positions the IRS as a dynamic and significant player in hair follicle biology, with important regulatory functions that have been previously underexplored.
