Biology of the Hair Follicle: The Basics

The document from 2006 explores the intricate biology of the hair follicle and its role in hair growth cycles, which consist of anagen, catagen, and telogen phases. It highlights the importance of stem cells in the regenerative nature of hair follicles and the influence of various signaling molecules on the hair growth cycles. The paper emphasizes the need to understand these molecular mechanisms to develop effective treatments for hair loss and unwanted hair growth, conditions that affect a significant portion of adults. It also discusses the hair follicle's utility as a model for studying other biological processes and the psychosocial impact of hair loss. Additionally, the document delves into the specifics of hair follicle cycling, the role of the hairless gene in catagen, and the influence of growth factors, hormones, and stress on hair growth. It particularly focuses on androgenetic alopecia, the process of hair follicle miniaturization, and the role of DHT, 5a-reductase, and androgen receptors in this condition. The document suggests that a better understanding of stem cell signals and the intrinsic hair cycle clock could lead to improved treatments for hair loss disorders.