Fig. 1. Microneedles 0.15 mm, 0.25 mm, 0.5 mm, and 1.0 mm in length were applied in 10 cycles for 3 weeks, and 0.5 mm length microneedles were applied in 3, 6, 10, 13 cycles for 3 weeks. (A) In the 10-cycle group, visual inspection of the 0.25 mm and 0.5 mm groups 3 weeks after the first microneedle stimulation revealed more prominent hair growth than that in the 0.15 mm and 1.0 mm groups. (B) In the 0.5 mm group, 10 cycles revealed the most prominent hair growth 3 weeks after the first microneedle stimulation.