Beyond Goosebumps: Does the Arrector Pili Muscle Have a Role in Hair Loss?

The document reviewed the arrector pili muscle's (APM) anatomy and potential involvement in hair loss, particularly androgenetic alopecia (AGA). The APM, which connects hair follicles to connective tissue, is known for its role in thermoregulation and piloerection and may also contribute to follicular integrity and hair cycle regulation. The review suggested that APM degeneration could lead to the detachment of the muscle from miniaturized follicles, potentially causing irreversible hair loss in AGA. It also proposed that fat degeneration within the APM might be a contributing factor, similar to fat degeneration in skeletal muscle pathologies. The interaction between the APM and follicle mesenchyme was hypothesized to be important for the hair cycle, with the degeneration of the APM possibly resulting from the loss of progenitor cell populations. The document concluded that more research is needed to fully understand the APM's role in hair growth and loss, its impact on hair transplantation, and the signaling between the APM and surrounding tissues.