Quantitative Models for the Study of Hair Growth In Vivo
December 1991
in “
Annals of the New York Academy of Sciences
”
hair growth in vivo histogenesis baldness stumptailed macaques morphometric method folliculograms alopecia hair follicles puberty androgen levels antiandrogens minoxidil 5% minoxidil 2% minoxidil 5α-reductase serum androgens hair weight frontal baldness fuzzy rats anagen follicles vellus telogen follicles androgenetic alopecia drug screening hair loss Propecia Rogaine androgenic alopecia DHT
TLDR The conclusion is that small hair follicles cause baldness in macaques, and treatments like antiandrogens and minoxidil can prevent hair loss and promote regrowth.
In 1991, researchers developed a quantitative method to study hair growth in vivo, focusing on the histogenesis of baldness in stumptailed macaques and using a morphometric method to create "folliculograms." They discovered that alopecia in macaques was due to smaller hair follicles, not fewer in number, and was linked to puberty and increased androgen levels. The condition could be prevented with antiandrogens. The study also found that 5% minoxidil was more effective than 2% in promoting hair regrowth and follicle size. A study with six macaques treated with an antiandrogen showed decreased 5α-reductase activity, unchanged serum androgens, and increased hair weight, preventing frontal baldness. Additionally, minoxidil treatment in fuzzy rats, a genetic model for hair growth, increased the size of anagen follicles and stimulated growth in dormant vellus telogen follicles. The document concludes that vellus follicles have the potential for regrowth, but continuous androgen effects can cause regression unless blocked locally. The macaque and rat models were deemed relevant for studying human androgenetic alopecia and for drug screening.
