TLDR Hair curliness is due to uneven distribution of different cortices within the hair fiber.
The study used scanning microbeam small angle X-ray scattering (SAXS) to analyze the nanostructure of keratin fiber arrangement in human hair, revealing that the curliness of hair is due to the inhomogeneous distribution of two types of cortices within the hair fiber. This structural inhomogeneity was consistent across different ethnic groups (African, Caucasian, and Asian), suggesting that the macroscopic curl shape originates from these internal differences. The research highlighted that the arrangement of intermediate filaments varied between the inner and outer sides of the hair's curvature, similar to findings in Merino wool, indicating the presence of different cortical types in human hair.
35 citations
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February 2003 in “Biochimica et Biophysica Acta (BBA) - General Subjects” Lead can help reveal and organize lipids in human hair.
53 citations
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September 1999 in “Journal of Synchrotron Radiation” Keratinous tissues have multiple structural layers, including ordered keratin and lipid granules.
63 citations
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December 1998 in “Biochimica et Biophysica Acta (BBA) - Protein Structure and Molecular Enzymology” The study improved understanding of keratin fiber structure by showing consistent microfibril diameter but varying distances and electron density profiles.
175 citations
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January 1995 in “Birkhäuser Basel eBooks” Human hair growth and structure are influenced by keratin proteins, genes, melanin, and lipids.
4 citations
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April 2019 in “Cosmetics” Hair stiffness is higher when it has more para-like cortical cells.
55 citations
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February 2014 in “Journal of Structural Biology” Human hair has a complex, variable structure with a consistent matrix and double-twist pattern.
2 citations
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October 2022 in “Journal of structural biology” Older thin hair is not just thinner but also has different shape, structure, and stiffness.
90 citations
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January 1979 in “International review of cytology” Wool follicles are complex, involving interactions between different cell types and structures.
4 citations
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January 2015 in “Sen'i Gakkaishi” Hair and wool strength is affected by the number and type of bonds in their protein structures, with hair having more protein aggregates than wool.
