The human scalp is covered with thousands of hair follicles, each follicle is responsible for the growth of between one and/or multiple strands of hair. While all hair follicles have the same basic structure and function, there are actually several different types of phases that follicles go through on the human scalp, each of which has its own unique characteristics and role in hair growth. In this article, we will explore the different phases and how they affect overall hair growth.
The first phase is the anagen phase, which is also known as the active growth phase for follicles. Typically, the majority of follicles on the scalp are in the anagen phase. The follicle is characterized by its elongated shape and the presence of a hair bulb at the base of the follicle. During the anagen phase, the hair bulb actively produces new cells, which are pushed upwards towards the surface of the scalp. As the cells reach the surface, they become keratinized and hardened, forming the hair strand. The anagen phase typically lasts for several years, and it is responsible for new hair growth on the scalp.
The second phase is the catagen phase. This phase is also known as the transitional phase for the follicle. Follicle’s in this phase are found in the upper layers of the dermis, and it is characterized by its shorter and more rounded shape. Catagen is a transitional phase between the anagen and telogen phases, and it typically lasts for only a few weeks.
During the catagen phase, the hair follicle undergoes a process of regression, where the hair bulb begins to shrink, and the hair strand becomes detached from the follicle. This process is known as “club hair,” and it is a crucial step in the hair growth cycle. Once the club hair is fully detached, the follicle enters the telogen phase.
The third type of phase of the hair follicle growth cycle is the telogen phase, which is also known as the resting phase. Follicles in this phase are found scattered in the upper layers of the dermis, and also have a short and rounded shape. The telogen follicle is a resting phase, where the hair strand is fully detached from the follicle and no new cells are produced. The telogen phase typically lasts for several months, and it is followed by a new anagen phase, where the hair strand is replaced by a new hair strand.
The number of hair strands per follicle unit varies among the different types of hair follicles on the human scalp. In general, follicles in the anagen phase have the highest number of hair strands per follicle unit. This is because the anagen follicles are actively producing new cells and pushing them upwards towards the surface of the scalp.
The follicles are in the catagen and telogen phase, they have a much lower number of hair strands per follicle unit. This is because these follicles are not actively producing new cells, and the hair strands are either in the process of detachment or are already detached from the follicle. In general, the catagen and telogen follicles have only a few hair strands per follicle unit, with some follicles producing as few as 1 or 2 hair strands.
Overall, the different phases of hair follicles on the human scalp play a crucial role in hair growth and hair loss. The anagen phase is responsible for the majority of hair growth, while the catagen and telogen phases play a crucial role in the hair growth cycle and the replacement of old hair strands with new ones. By understanding the different types of hair follicle phases and their role in hair growth, we can better understand the causes and treatments of hair loss.
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