Differences in Hair Follicle Dermal Papilla Volume Are Due to Extracellular Matrix Volume and Cell Number: Implications for the Control of Hair Follicle Size and Androgen Responses

The study examined 235 hair follicles to explore the relationship between hair follicle size and dermal papilla volume, focusing on cell number and extracellular matrix volume. It found that male facial follicles had a dermal papilla volume nearly 40 times greater than female facial follicles, attributed to a 17-fold increase in cell number and a 2.4-fold increase in volume per cell. The research suggested that androgen-induced hair follicle enlargement involves increases in both cell number and extracellular matrix volume, with cell number having a larger impact. This challenges the belief that dermal papilla cell numbers are fixed during embryogenesis, proposing instead that cell proliferation or recruitment occurs during hair transition. The findings highlighted the dermal papilla's crucial role in androgen-mediated hair growth changes.