External root sheath

Definition

The external root sheath is a layer of the hair follicle that provides a protective sleeve around the hair shaft, extending from the skin surface to the hair bulb. It is composed of epithelial cells and plays a crucial role in hair growth and regeneration.

Related terms

Hair Follicle:

A dynamic organ found in mammalian skin that produces hair through a complex cycle of growth, regression, and rest.

Hair Shaft: The visible part of the hair that extends above the skin's surface, composed of dead keratinized cells.

Keratinocytes:

Epithelial cells which produce keratin, a key protein that makes up the structure of the skin, nails, and hair