Which stage of hair growth involves keratinization to form a club hair?

The stage of hair growth that involves keratinization to form a club hair is the catagen phase. During this transitional stage, the hair follicle undergoes significant changes. The catagen phase typically follows the anagen phase (growth phase) and precedes the telogen phase (resting phase).

During catagen, the lower part of the hair follicle shrinks and detaches from the dermal papilla, leading to the hair being cut off from its blood supply. This process initiates keratinization, whereby the cells in the hair shaft become more keratinized, resulting in the formation of club hair. The club hair is a type of hair that is no longer actively growing, and its connection to the follicle diminishes until it eventually falls out or is shed during the telogen phase.

Understanding this process is vital for those studying electrology, as it provides insight into hair growth cycles and informs treatment decisions regarding hair removal and management.