Each hair grows from, and through , an individual follicle which surfaces on your scalp. Is is essential that the follicle and the scalp, at point of exit, are clean, clear, and healthy. Follicles that are full of sebum or blocked by dead skin, dandruff or infection will have an impact on the quality of hair growth. In fact , permanently blocked or obstructed follicles may eventually cease to produce hair at all.