Fundamentals of Hair and Follicles

The human scalp contains up to 150,000 hair follicles. Hair anatomy and growth cycles are essential components to understand and treat hair loss. Diseases that affect any part of the follicle can lead to hair loss and temporal or permanent alopecia. Androgenic alopecia is the most frequent form of hair loss in adults. Herein, we describe the hair anatomy and basic growth cycles in order to understand the basis of hair transplantation and several diseases that are characterized by hair loss.