Stiffness of Human Hair Correlates with the Fractions of Cortical Cell Types

April 2019 in “ Cosmetics ”

Yusuke Ezawa, Shinobu Nagase, Akira Mamada, Shigeto Inoue, Kenichi Koike, Takashi Itou

hair stiffness bending modulus para-like cortical cells ortho-like cortical cells macrofibrils intermacrofibrillar materials

Studysummary In this study, the bending stiffness of human hair was linked to the varying proportions of para-like versus ortho-like cortical cells within the hair fiber. Our plain-language summary of this paper — not a Tressless recommendation.

The study investigated the relationship between hair stiffness and its microstructure in 156 Japanese women. It found that hair stiffness, measured by bending modulus, was significantly higher in hair rich in para-like cortical cells. The bending modulus correlated with the fraction of para-like cortical cells, while the elastic moduli inside macrofibrils were similar for both para- and ortho-like cortical cells. The differences in hair stiffness were attributed to the intermacrofibrillar materials associated with the different cortical cell types.

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