TLDR Stem cells are present in plucked hair follicles and can be maintained in culture.
This study investigated the presence of stem cells in plucked hair follicles by examining their cytokeratin (CK) profiles and apoptosis-related proteins. Researchers found that cells expressing CK19 and the apoptosis-suppressing protein Bcl-2, but not the apoptosis-promoting protein Bax, were present in specific areas of the hair follicle and in cultured follicular cells. These findings suggested that CK19/Bcl-2-positive and Bax-negative cells, potentially representing follicular stem cells, could be derived from plucked hair and maintained in culture. The study supported the hypothesis that stem cells are located in the bulge area of the hair follicle, rather than near the dermal papilla.
31 citations
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September 1996 in “Differentiation” The upper dermal sheath can regenerate hair in rats.
441 citations
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May 1996 in “Journal of Cell Science” Keratin 19 helps identify skin stem cells, with its presence varying by body location, age, and culture stage.
94 citations
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March 1996 in “Journal of Investigative Dermatology” 
253 citations
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March 1994 in “Developmental dynamics” Apoptosis is essential for human skin development and forming a functional epidermis.
28 citations
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July 1993 in “The journal of investigative dermatology/Journal of investigative dermatology” Dermal papilla cells are crucial for hair growth and can induce new hair follicles.
238 citations
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May 1989 in “Journal of Investigative Dermatology”
18 citations
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January 2013 in “Veterinary Dermatology” K15 is a reliable marker for studying stem cells in dog hair follicle tumors.
82 citations
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May 2004 in “British Journal of Dermatology” Stem cells are present in plucked hair follicles and can be maintained in culture.
10 citations
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October 2000 in “PubMed” E6/E7 oncogenes in hair follicles cause continuous hair growth by skipping the resting phase.
94 citations
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February 1994 in “The journal of investigative dermatology/Journal of investigative dermatology” EGF makes hair follicles grow longer but stops hair production.
59 citations
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August 1981 in “PubMed” Trichilemmal keratinization is a unique process in hair follicles where the outer root sheath turns into keratin without a specific layer.
