To facilitate counting, hairs in a 1×1 cm2 area on the specific area of the scalp (in 1 of 4
quadrants of the frontoparietal / occipitoparietal scalp) will be clipped adjacent to the scalp near the roots of the hair at T0, T+4 weeks, T+8 weeks, T+12 weeks and T+16 weeks. This region will be sequestered by applying a plastic template to the scalp surface to ensure reproducibility. The template defined a square region with a width of 1 cm thus an area of 1×1 cm2 of the scalp will be used for hair counting