The Hair Follicle: Functions, Self-Renewal, and Alopecic Disorders

The document from March 21, 2016, discusses the various functions of the hair follicle (HF), including thermoregulation, protection, sensory perception, social interactions, and camouflage. It highlights the ability of HFs to self-renew through the hair cycle (HC) to produce new hair throughout an individual's life. The document notes that disturbances in the HC are common and can lead to alopecic disorders, which are also observed in dogs. The maintenance of a normal HC is attributed to follicular stem cells (SCs), primarily located in the bulge area of the follicle. The review suggests that due to the morphological similarities between human and canine bulge areas, as well as similarities in follicular biomarker expression, dogs could serve as a promising model for studying human HC and SC disorders. The review provides an overview of follicular anatomy, the HC, follicular SCs, and discusses potential mechanisms of noninflammatory alopecia.