Exogen Involves Gradual Release of the Hair Club Fiber in the Vibrissa Follicle Model

January 2009 in “ Experimental Dermatology ”

Claire A. Higgins, Gavin D. Richardson, Gillian Westgate, Colin A.B. Jahoda

exogen phase hair cycle hair club fiber vibrissa follicle model outer root sheath ORS anagen follicles early anagen late anagen epithelial sac hair shedding hair growth cycle hair fiber whisker follicle model growth phase early growth phase late growth phase skin sac

TLDR Hair sheds gradually from the follicle, with readiness to shed indicated by less attachment material.

The study investigated the exogen phase of the hair cycle, which is the shedding of the hair club fiber, using the vibrissa follicle model from rodents. The researchers discovered that the amount of outer root sheath (ORS) material on the club fiber after plucking was indicative of the time until natural release. They observed that 66% of club fibers from early anagen follicles had a significant amount of cellular material, suggesting immaturity for release, while 81% of club fibers from late anagen follicles had little to no cellular material, indicating readiness for release. This led to the suggestion of dividing exogen into 'early exogen' and 'late exogen' based on club fiber adhesion states. The study concluded that the vibrissa follicle model is effective for studying exogen and that club fiber release involves a gradual loosening from the epithelial sac.

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Exogen Involves Gradual Release of the Hair Club Fiber in the Vibrissa Follicle Model

Research cited in this study

research Exogen Hair Characterization in Human Scalp

research Kenogen in Female Androgenetic Alopecia

research Exogen, Shedding Phase of the Hair Growth Cycle: Characterization of a Mouse Model

research Growth of the Hair

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