Exogen, Shedding Phase of the Hair Growth Cycle: Characterization of a Mouse Model
September 2002
in “Journal of Investigative Dermatology”
TLDR Researchers found that hair shedding happens mostly when new hair is growing and involves a unique process.
In 2002, researchers characterized the exogen phase of the hair growth cycle, which is the shedding phase, using a mouse model. They developed methods to collect and quantify shed hair, discovering that shedding is most pronounced during the anagen phase and that the shed hair originates from a previous cycle. The study found that the base of shed hair has a unique morphology, suggesting a proteolytic process is involved in shedding. The findings indicate that exogen is a distinct phase, coupled to anagen, and that shedding is not advantageous before new hair has grown. The study did not specify the number of mice used, but it laid the groundwork for future research into the exogen phase.
View this study on jidonline.org →
Cited in this study
research Localization of Plasminogen Activator Inhibitor Type 2 (PAI-2) in Hair and Nail: Implications for Terminal Differentiation
PAI-2 helps in the maturation and protection of hair and nail cells.
research Growth of the Hair
Hair growth is cyclic and influenced mainly by local factors.
Related
research Blockade of S100A3 activity inhibits murine hair growth
Stopping S100A3 activity slows down hair growth in mice.
research Exogenous stimulations change nude mouse hair cycle pattern
The study investigated the impact of exogenous stimulations on the hair growth pattern of nude mice, revealing that hair growth occurred in waves from the head to the posterior back. Male nude mice exhibited a more regular hair cycle pattern than females. Exogenous stimulations significantly extended the hair-existing phase and reduced the no-hair phase without altering the overall hair growth pattern. Topical minoxidil was most effective in males, while in females, wounds were more effective than minoxidil in prolonging the hair-existing phase, though the effect was not pronounced.
research Treatment of Hair Loss
Finasteride and minoxidil are effective for hair loss, but continued research is needed for better treatments.