Hair follicles

Constitute

The hair follicle is a sheath-like structure around the hair root, which consists of inner hair root sheath, outer hair root sheath and fibrous sheath from inside to outside.

1. Inner hair root sheath

The inner hair root sheath originates from the epidermis and is divided into three layers from inside to outside, namely sheath skin, Huxley layer and Henler layer. The sheath skin, also known as the sheath cuticle, is a layer of overlapping cells; the Huxley layer is composed of 1-3 layers of cells; and the Henler layer is composed of flat cells arranged in a single row.

2. Outer hair root sheath

The outer hair root sheath originates from the epidermis and consists of one or more layers of cells. The outer layer is rectangular columnar epithelial cells.

3. The fibrous sheath

The fibrous sheath originates from dermis and can be divided into three layers. The inner layer is a transparent glass-like film. The middle layer is composed of dense and wavy fibrous tissue. The outer layer is composed of collagen fibers and elastic fibers. There is no obvious boundary between the fibrous sheath and the surrounding connective tissue.

Function

Hair grows from hair follicles, which absorb nutrients from the body to support hair growth. Epithelial cells of hair follicle tissue can divide and reproduce, which makes hair change and grow continuously. However, with the increase of age, the function of hair follicle gradually weakens, and the phenomenon of hair loss occurs.