When you think about the roots of your hair, you may think of the hair found at the base of the scalp. However, the root of the hair, despite popular belief, is actually found underneath the skin. Hair roots are found in the the second layer of skin, the dermis, where the hair growth and coloration takes place. In fact, the science of hair growth and regrowth all take place in the root of the hair, unseen to our eyes.
The root of our hair is found in the hair follicle, which is the birthplace of your hair growth. The tunnel-like segment extends from the epidermis, the first layer of skin, down into the deeper level of the skin called the dermis. The structure of the follicle contains many layers with separate functions belonging to each layer. Let’s take a look at the several components of your hair follicle and the role they play in hair growth and regrowth.
The dermal papilla is located at the base of the hair follicle. Buried approximately 4 milimeters down into the scalp, the papilla is the driving force of the follicle. Through several tiny blood vessels, or capillaries, the papilla proves the nutrients and information necessary for the multiplication and differentiation of the hair cells. This nourishment from the papilla helps regulate the life cycle of your hair, providing hair health and helping you grow your hair.
Located around the papilla, the pilar matrix is the deepest component of the hair follicle. It is within the matrix that the hair cells, known as keratinocytes, begin to multiply and differentiate. As these cells divide, the different compartments of the hair follicle- internal root sheath, external root sheath and hair shaft- begin to form. The keratinocytes differentiate at a much faster rate than any other cells in the body, dividing every 24 to 72 hours. The fast rate of these cell differentiations is why chemotherapy or radiotherapy, which kill dividing cells, may lead to temporary hair loss.
Internal Root Sheath
The internal sheath, formed by the piler matrix, surrounds the growing hair shaft. Since the hair shaft is soft and fragile during the beginning stages in the hair growth cycle, the internal root sheath serves as support and protection. This internal sheath follows the shaft, ending just below the opening of a sebaceous gland.
External Root Sheath
Continuous with the epidermis, the external root sheath surrounds the internal sheath and the hair shaft. The external root sheath also contains the outermost layer of cells, which are activated by the dermal papilla during the restart of the hair growth cycle to enable the reconstruction of the hair follicle and new hair growth.
Erector Pili Muscle
Connected to a fibrous layer around the outer root sheath is the erector pili muscle. Under the influence of emotional response, this muscle can contract, causing the hair on your head to stand up. The contraction of this muscle can also cause the release of oil from the sebaceous gland.
Each of your hair follicles have at least one of more sebaceous glands. These oil glands contain large cells known as sebocytes which are filled with lipid droplets. When sebocytes burst, they release sebum, which is essential for protecting your hair and preserving is shine and flexibility.
The central part of the hair follicle is the hair shaft. Surrounded by the outer and inner root sheath, the hair shaft is pushed towards the surface of the skin by the cells multiplication and differentiation within the pilar matrix. The hair shaft is composed of three parts: the medulla, the cortex and the cuticle. It is made up of keratinocytes, which die at 0.5 millimeters from the base of the follicle. The formation of the shaft is completed as it passes the sebaceous gland. It is then released from the root sheath as it pushes its way through the surface, making it the part of the hair we see everyday.
At Benoté, we believe, not only in hairstyle execution but, in hair education. It is our job and our privilege to have you as a client / potential client. We hope that by helping you to understand your hair, we can help you maintain your healthy hair for the rest of your life. Remember, we’re not just a salon. Benoté is an experience.