The Inner and Outer Root Sheaths, Including the Huxley and Henle Layers
Structure of the hair shaft Figure 6: The Parts of the Hair Shaft in Cross-Section: the Cuticle, Cortex, and Medulla
Figure 8: The Structure of the Hair Follicle
Note . Beautybynature.com
The hair root The hair root is the production unit for the hair shaft, consisting of six main components: the hair follicle, dermal papilla, hair bulb, sebaceous glands, and arrector pili muscle. The hair root is a multifaceted unit, beginning at the top layer of the epidermis and reaching through the reticular layer of the dermis into the subcutaneous tissue (Milady, 2023). The structures of the hair root depress deep throughout the five layers of the epidermis—the corneum, lucidum, granulosum, spinosum, and germination layer. It continues to push through the two layers of the dermis— the papillary and reticular layer—with the bottom of the structure ending within the adipose tissue beneath the skin. This information strongly supports how only healthy skin can produce healthy hair strands (Milady, 2023). Figure 7: The Hair Root
Note . Drclementlo.com
From the view of the epidermis, the hair follicle shows a pocket on the scalp containing the hair shaft. Viewing the hair follicle from inside the skin reveals a tube-like depression deep within the layers of the skin. The hair follicle grows around the dermal papilla and upward throughout the hair root structure onto the top of the skin’s surface (Milady, 2023). Brannon (2023) reported that hair follicles are all over the body, only absent in the palms of the hands and soles of the feet. More than 5 million hair follicles are present in human bodies. Of those, over 1 million follicles are present on the heads of humans. Hair follicles are identifiable among human fetuses within 22 weeks. Hair follicles do not regrow. The amount of hair follicles an individual is born with is the only number of follicles the person will have throughout their lifetime. As people age, the life of their hair follicles decreases, causing a loss of density in their hair. The dermal papilla is the lowest part of the hair root, located at the base of the hair follicle. The dermal papilla, also known as the mother of hair, contains the essentials for hair life by providing the needed nutrients for hair growth, such as blood vessels and nerve endings. The dermal papilla is cone-shaped, with a small elevation at the bottom of the hair follicle, fitting into the bulb. The hair bulb is a hollow club-like structure forming at the lower part of the hair follicle within the hair root, covering the dermal papilla. The hair bulb disperses the first evidence of growing hair (Milady, 2023). Sebaceous glands are groups of oil-producing, saclike structures attached to the hair follicle and consisting of ducts that secrete sebum (Milady, 2023). Sebaceous glands support normal skin functioning by providing an oily residue on the skin surface and keeping hair follicles soft and moist. Hormones, blood circulation, diet, certain medications, and emotional disturbances like stress influence sebum production. Hormones vary in their influence on the sebaceous gland. The androgen hormone increases sebum production, while estrogen decreases the activity of the sebaceous glands (HealthHype, 2023). Below the sebaceous gland is the arrector pili muscle. The arrector pili is a tiny muscle attached to the bottom of the hair follicle. The arrector pili is an involuntary muscle, a sensory mechanism, reacting when the skin identifies a chilling sensation and often for reasons unknown (Milady, 2023). During times of various sensations, the arrector pili
Note . Rogaine.com
The hair follicle houses and protects the production of the hair shaft. The hair follicle is not a single-tissue construction. It is an intricate system that shapes and protects the creation of the hair strand (Milady, 2023). Brannon (2023) highlighted the hair follicles’ inner and outer root sheaths. The sheaths of the follicle are living tissues surrounding the hair follicle. Ruberte et al. (2023) introduced the inner and outer root sheaths as two layers of horny, flattened nucleated cells, the Huxley and Henle layers. The two layers mold and protect the developing hair strand within the inner sheath of the hair follicle.
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