Keratin network modifications lead to the mechanical stiffening of the hair follicle fiber

Researchers used atomic force microscopy to measure the mechanical properties of the human hair follicle and found significant stiffening within the first millimeter. This stiffening was linked to changes in the keratin network's architecture and composition. In early keratinization stages, the thickening, densification, and increasing orientation of fibers caused the stiffening, while in later stages, intermolecular cross-linking became more important. These findings supported known biological and structural events during hair keratinization and highlighted the connection between the hair follicle's mechanical properties and its multiscale tridimensional organization.