Outer root sheath

The Outer Root Sheath (ORS) is a component of the hair follicle that plays a crucial role in hair growth and development. It is the outermost layer of the hair follicle and is continuous with the epidermis and the sebaceous gland ducts.

Structure

The Outer Root Sheath is composed of two layers: the outermost layer, which is continuous with the epidermis, and the inner layer, which is a direct continuation of the stratum granulosum of the epidermis. The ORS does not produce keratin, unlike the Inner Root Sheath (IRS) and the hair shaft.

Function

The ORS serves several important functions in the hair follicle. It provides a pathway for the growing hair shaft, and it also plays a role in the cyclic growth of the hair follicle. The cells of the ORS are involved in the formation of the new hair shaft and the IRS during the anagen phase of the hair growth cycle.

Clinical significance

Abnormalities in the ORS can lead to a variety of hair disorders. For example, mutations in the genes that regulate the development and function of the ORS can cause alopecia, a condition characterized by hair loss. In addition, the ORS is the site of origin for several types of skin cancer, including basal cell carcinoma and squamous cell carcinoma.

See also

• Hair follicle
• Inner Root Sheath
• Epidermis
• Sebaceous gland
• Anagen
• Alopecia
• Basal cell carcinoma
• Squamous cell carcinoma