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Androgenetic alopecia: new insights into the pathogenesis and mechanism of hair loss.

Sinclair R, Torkamani N, Jones L - F1000Res (2015)

Bottom Line: The hair follicle is a complete mini-organ that lends itself as a model for investigation of a variety of complex biological phenomena, including stem cell biology, organ regeneration and cloning.  The arrector pili muscle inserts into the hair follicle at the level of the bulge- the epithelial stem cell niche.  The arrector pili muscle has been previously thought to be merely a bystander and not to have an active role in hair disease.Computer generated 3D reconstructions of the arrector pili muscle have helped explain why women with androgenetic alopecia (AGA) experience diffuse hair loss rather than the patterned baldness seen in men.  Loss of attachment between the bulge stem cell population and the arrector pili muscle also explains why miniaturization is irreversible in AGA but not alopecia areata.A new model for the progression of AGA is presented.

View Article: PubMed Central - PubMed

Affiliation: Department of Medicine, University of Melbourne, Victoria, Australia ; Epworth Dermatology, Victoria, Australia ; Sinclair Dermatology, Victoria, Australia.

ABSTRACT
The hair follicle is a complete mini-organ that lends itself as a model for investigation of a variety of complex biological phenomena, including stem cell biology, organ regeneration and cloning.  The arrector pili muscle inserts into the hair follicle at the level of the bulge- the epithelial stem cell niche.  The arrector pili muscle has been previously thought to be merely a bystander and not to have an active role in hair disease. Computer generated 3D reconstructions of the arrector pili muscle have helped explain why women with androgenetic alopecia (AGA) experience diffuse hair loss rather than the patterned baldness seen in men.  Loss of attachment between the bulge stem cell population and the arrector pili muscle also explains why miniaturization is irreversible in AGA but not alopecia areata. A new model for the progression of AGA is presented.

No MeSH data available.


Related in: MedlinePlus

Scalp follicles exist as compound follicular units.In androgenetic alopecia, miniaturization occurs initially in the secondary follicles. This leads to a reduction in hair density that precedes visible baldness. Bald scalp becomes visible only when all of the hairs within a follicular unit are miniaturized. With miniaturization, the muscle initially loses attachment to the secondary follicles. When primary follicles eventually miniaturize and lose muscle attachment, the hair loss becomes irreversible.
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f10: Scalp follicles exist as compound follicular units.In androgenetic alopecia, miniaturization occurs initially in the secondary follicles. This leads to a reduction in hair density that precedes visible baldness. Bald scalp becomes visible only when all of the hairs within a follicular unit are miniaturized. With miniaturization, the muscle initially loses attachment to the secondary follicles. When primary follicles eventually miniaturize and lose muscle attachment, the hair loss becomes irreversible.

Mentions: In conclusion, we propose a new model for AGA (Figure 10). In early stages of hair loss, the APM remains attached to the primary follicle but loses its attachment to some of the regressing secondary follicles in some FUs. Miniaturization of secondary follicles and detachment of the APM from these follicles extend to the rest of the FUs. At this stage, patients may complain of hair thinning and loss of volume in their pony tail without visible baldness.


Androgenetic alopecia: new insights into the pathogenesis and mechanism of hair loss.

Sinclair R, Torkamani N, Jones L - F1000Res (2015)

Scalp follicles exist as compound follicular units.In androgenetic alopecia, miniaturization occurs initially in the secondary follicles. This leads to a reduction in hair density that precedes visible baldness. Bald scalp becomes visible only when all of the hairs within a follicular unit are miniaturized. With miniaturization, the muscle initially loses attachment to the secondary follicles. When primary follicles eventually miniaturize and lose muscle attachment, the hair loss becomes irreversible.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4544386&req=5

f10: Scalp follicles exist as compound follicular units.In androgenetic alopecia, miniaturization occurs initially in the secondary follicles. This leads to a reduction in hair density that precedes visible baldness. Bald scalp becomes visible only when all of the hairs within a follicular unit are miniaturized. With miniaturization, the muscle initially loses attachment to the secondary follicles. When primary follicles eventually miniaturize and lose muscle attachment, the hair loss becomes irreversible.
Mentions: In conclusion, we propose a new model for AGA (Figure 10). In early stages of hair loss, the APM remains attached to the primary follicle but loses its attachment to some of the regressing secondary follicles in some FUs. Miniaturization of secondary follicles and detachment of the APM from these follicles extend to the rest of the FUs. At this stage, patients may complain of hair thinning and loss of volume in their pony tail without visible baldness.

Bottom Line: The hair follicle is a complete mini-organ that lends itself as a model for investigation of a variety of complex biological phenomena, including stem cell biology, organ regeneration and cloning.  The arrector pili muscle inserts into the hair follicle at the level of the bulge- the epithelial stem cell niche.  The arrector pili muscle has been previously thought to be merely a bystander and not to have an active role in hair disease.Computer generated 3D reconstructions of the arrector pili muscle have helped explain why women with androgenetic alopecia (AGA) experience diffuse hair loss rather than the patterned baldness seen in men.  Loss of attachment between the bulge stem cell population and the arrector pili muscle also explains why miniaturization is irreversible in AGA but not alopecia areata.A new model for the progression of AGA is presented.

View Article: PubMed Central - PubMed

Affiliation: Department of Medicine, University of Melbourne, Victoria, Australia ; Epworth Dermatology, Victoria, Australia ; Sinclair Dermatology, Victoria, Australia.

ABSTRACT
The hair follicle is a complete mini-organ that lends itself as a model for investigation of a variety of complex biological phenomena, including stem cell biology, organ regeneration and cloning.  The arrector pili muscle inserts into the hair follicle at the level of the bulge- the epithelial stem cell niche.  The arrector pili muscle has been previously thought to be merely a bystander and not to have an active role in hair disease. Computer generated 3D reconstructions of the arrector pili muscle have helped explain why women with androgenetic alopecia (AGA) experience diffuse hair loss rather than the patterned baldness seen in men.  Loss of attachment between the bulge stem cell population and the arrector pili muscle also explains why miniaturization is irreversible in AGA but not alopecia areata. A new model for the progression of AGA is presented.

No MeSH data available.


Related in: MedlinePlus