TLDR Hair structure forms the same way inside and outside the body.
The study used synchrotron X-ray micro-diffraction to examine the keratinization process in human hair follicles, revealing that molecular organization, specifically the formation of alpha-helices, was completed inside the follicle, while supramolecular organization and filament structure appeared outside the follicle. Comparisons between in vitro and in vivo grown hair showed no structural differences, indicating that the keratinization process was consistent regardless of the growth environment.
19 citations
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April 2015 in “International Journal of Molecular Sciences” The research identified genes and pathways important for sheep wool growth and shedding.
73 citations
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May 2009 in “Proceedings of the National Academy of Sciences” The study established that the disruption of the Sox21 gene in mice led to a cyclic alopecia phenotype, characterized by progressive hair loss and eventual regrowth. Sox21 was found to be crucial for the differentiation of the hair shaft cuticle, as its absence resulted in the loss of interlocking structures necessary for anchoring the hair shaft, leading to hair loss. Additionally, the expression of genes related to keratins and keratin binding proteins in the hair shaft cuticle was down-regulated in Sox21-null mice. This research highlighted Sox21 as a key regulator of hair shaft cuticle differentiation and provided insights into potential causes of human hair disorders.
January 2006 in “Chinese Journal of Dermatology” 276 citations
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January 2005 in “International review of cytology” 199 citations
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January 2004 in “The International Journal of Developmental Biology” Hair follicle growth and development are controlled by specific genes and molecular signals.
28 citations
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July 2000 in “PubMed” Hair structure forms the same way inside and outside the body.
6 citations
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October 1988 in “Clinics in Dermatology” 
34 citations
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August 1966 in “Experimental cell research” Keratin fibrils in hair form and stop growing at specific points in the follicle.
