Identification of novel telogen markers underscores that telogen is far from a quiescent hair cycle phase

In contrast to the dynamic and striking changes in hair follicle (HF) morphology during the anagen and catagen phases of the hair cycle, the telogen follicle appears static. However, it has been argued that the quiescent appearance of telogen HFs is deceptive (Davis 1962, Stenn, Paus 2001, Higgins, Westgate 2009). For example, the expression of some genes clearly peaks during telogen (Greco, Chen et al. 2009). Also, functionally distinct subphases of telogen have been identified (“competent” versus “refractory telogen”) based on the ability to initiate anagen after plucking (Plikus, Mayer et al. 2008).