Primary Hair Cells

Here you can find dermal papilla cells, germinal matrix cells and follicular outer root sheath cells.

The dermal papilla is a highly active group of cells. It is derived from the dermis mesenchyme, located at the base of the hair follicle. The dermal papilla is implicated in controlling the hair growth cycle; dermal papilla cells are capable of inducing follicle development from the epidermis and the production of hair fiber. Early passage dermal papilla cells can induce hair growth in vivo, but, upon further culturing, this property is lost. Hair growth is tightly regulated by the epithelial-mesenchymal interaction of hair follicle cells.

The Germinal matrix is an area of reproducing cells situated around the papilla at the base of the hair bulb. It is the source of hair growth and is involved in transfering melanin to hair to give it pigmentation. During the active hair growth phase, cells in the matrix rapidly grow and differentiate, causing the hair to elongate. Cells of the germinal matrix under go a process called keratinization, which is the formation of a layer of the protein keratin, keeping the hair from falling out.

The outer root sheath (ORS) of the hair follicle surrounds the hair fiber and inner root sheath. It is distinct from other epidermal components being continuous with the surface epidermis. The ORS consists of several layers of cells that can be identified with unique ultrastructural properties; plays a part in certain functions of the hair follicle, including acting as the sensory organ and immunologic sentinel of the skin.