One of rarely discussed topics is underarm hairs. Many people consider these hairs to be problematic and thus, get them removed through various procedures. Underarm hairs are considered as important as they act as collector and insulator.
It is on these hairs that pheromones get collected. This is the reason why underarm hairs are thicker than hairs present on scalp or hand. Pheromones are the chemicals that are used for transmitting the subconscious sexual information to other members. Very often, people use deodorants on underarm hairs and thus, pheromones are not able to perform any role.
Underarm hairs grow in stages. These hairs vary considerably with respect to thickness, abundance, texture and color. Some women may have abundant, dark and coarse underarm hairs while other women may have only a light smattering of these hairs. All the stages of underarm hairs are found growing in the hollow area of armpit.
However, these hairs can also grow on other areas of underarm. First or initial stage of underarm hairs can appear at the age of 8 to 13 years and. As the stage of underarm hairs change, their texture, color and thickness also change. One aspect that should be understood here is that presence of underarm hairs in girls means they are transitioning into puberty and thus, all other associated developments are going to take place.
Stage of puberty continues for several years and at the end of this stage, a girl becomes sexually mature. Same is the case with boys. In puberty stage, all the stages of underarm hairs are generally noticed. Changes being made in stage of underarm hairs is generally accompanied with development of breast, change in height, and deposition of fat at hips and thighs. Change in stages of underarm hairs also lead to a peculiar underarm odor, which increases as a person reaches puberty. Apart from stage, thickness of underarm hairs depends upon genes also.
Stages of Underarm Hairs
Skin is basically composed of two layers. These are epidermis and dermis. Epidermis is the outermost layer of skin while dermis lies deep inside the skin. Underarm hairs are seen on epidermis but their follicles lie deep in the dermis layer. Various stages of underarm hairs pass through these two layers only.
Hair Follicle Stage is the first or initial stage of underarm hairs.
This stage lies within the dermis only and this is the reason why it is not visible to naked eye. Hair follicle stage can start at the age of 8 to 10 years. At this stage, no shaft of hair is formed and thus, follicle remains inside dermis only. These hair follicles are attached to a sebaceous gland called as ‘sebum’. This gland is made of fat cells and can be related directly to the odor of underarm hairs. However, sebum itself does not contain any odor.
Odor of underarm hairs is due to the bacterium that is attached to these glands. Since sebum is an oily substance, it prevents skin from drying up. Next stage of underarm hairs is Hair Shaft Stage. This stage is characterized by formation of hair shaft. Innermost part of hair shaft is called as medulla. In this stage, hair follicle continues to grow. As a result, length of medulla as well as hair shaft increases.
Due to increase in length, thickness of hair is also reduced. It generally happens when the hair shaft gets close to the epidermis layer. In the hair shaft stage, complete growth of hair is dependent upon the nutrients and other substances supplied by the surrounding blood vessels. In some cases, when blood vessels do not supply enough nutrients, hair shaft may remain underdeveloped.
Last stage of underarm hairs is called as Epidermis Growth Stage. As the name suggests, this stage occurs at the outermost layer of skin-epidermis. When the hair shaft increases in length considerably, it emerges out of epidermis layer. Decrease in thickness of hair follicle also helps in emerging out. However, growth of hair shaft occurs continuously. After growing up to a certain length, the growth of hair stops.
At this point of time, underarm hairs gain considerably thickness. When underarm hairs are plucked, a pain is felt. It occurs due to separation of hair follicle from the nerve endings. If underarm hairs are shaved at this stage, they grow again and their length increase up to previous levels only. Though a person progresses in age, length of hair shaft does not increase after a certain length.
This length depends upon many factors like heredity. At the epidermis growth stage, underarm hairs become fully grown. Unit of fully grown hairs is also called as Pilisebaceous Unit. This unit is composed of hair shaft, follicle, sebaceous gland and Arrector Pili Muslce. This is the muscle that controls the erection levels of underarm hairs. There are some phenomenons during which use of this muscle can be experienced. For example, Goose Bump is one of them.
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