Final answer:
The transitional phase in hair growth is the catagen phase, lasting 2 to 3 weeks, when the hair follicle shrinks and prepares for shedding. This phase follows the anagen growth phase and precedes the telogen resting phase.
Step-by-step explanation:
The stage of hair growth considered the transitional phase is called the catagen phase. The catagen phase signifies the end of the active growth phase, known as the anagen phase. During the catagen phase, which lasts approximately 2 to 3 weeks, the hair follicle shrinks and detaches from its blood supply, setting the stage for the eventual shedding of the hair.
In the broader context of hair growth, each hair follicle undergoes a cycle that consists of three main stages: anagen, catagen, and telogen. At the conclusion of the anagen phase, during which a new hair is formed and grows, the catagen transitional phase occurs, paving the way to the resting phase, known as telogen. This cycle is a harmonious balance that maintains consistent hair density when hairs that are shed are replaced by new growth emerging from the hair matrix in the follicle. The cortex of a hair is the second or middle layer of keratinocytes that originate from the hair matrix and can be seen in a cross-section of the hair bulb.
Understanding the catagen phase is vital when studying hair biology, as this is when the hair follicle prepares for rest and eventual renewal. The cyclical nature of these phases ensures the regeneration and maintenance of hair over time.