Environment of the Anagen Follicle.

Hair follicles are part of the skin. Almost universally, follicles are described as an epithelium-derived tubular down growth into the skin's dermis. Because follicles are complex structures, especially when in anagen phase and configured to actively grow fibres, it is easy to forget that they are part of a crowded environment within the skin. This chapter introduces some of the structures which surround the follicle as well as some of the peripheral parts of the follicle, including follicle groups, and the dermal sheath, vasculature, adipocytes, nerves and the arrector pili muscle.