Anatomical structures of the hair root
The hair root is made up of several anatomical structures, each of which has a specific function in hair growth. These include the hair bulb with the dermal papilla, the hair matrix, the inner and outer root sheath, and accompanying connective tissue. These structures work together to supply, grow, stabilize, and regenerate the hair.
Hair bulb:
The thickened end of the hair root, also called the “hair bulb,” is located deep in the dermis or subcutis. In this area, the hair root surrounds the dermal papilla, which serves as the central supply and control organ for hair growth. This is where the actual growth area is located, where the matrix cells constantly divide and form new keratinocytes. At the same time, pigments are stored in this section by the melanocytes, determining the hair color.
Dermal papilla:
The dermal papilla itself is a connective tissue structure rich in blood vessels and nerves. This supply provides the hair matrix with all the important nutrients, oxygen, and special growth factors necessary for continuous cell division. At the same time, the dermal papilla acts as a control center for hair growth and the entire hair cycle by sending signals to activate, rest, or terminate the growth phase.
Hair matrix (growth zone):
Directly above the papilla lies the “hair matrix”:/en/haarmatrix.html, the actual growth zone of the hair. It contains highly active matrix cells that divide continuously and form new keratinocytes, which make up the hair shaft. This structure also contains melanocytes, which produce the pigment melanin and pass it on to the keratinocytes. This is how each hair gets its characteristic color, which is determined by the amount and type of melanin stored.
Inner root sheath:
The hair root is also surrounded by the inner root sheath. This layer of cells stabilizes the hair shaft within the follicle and ensures that it remains securely embedded as it grows upward. However, once the hair reaches the skin surface, the “inner root sheath”:/en/inner-root-sheath.html inner root sheath is no longer needed and gradually detaches.
Outer root sheath:
The “outer root sheath”:/en/outer-root-sheath.html surrounds the entire hair follicle and merges seamlessly into the epidermis of the skin. It not only serves as a protective covering, but also has a special biological significance: it contains stem cells that act as an important reserve for regeneration. These stem cells are capable of renewing damaged tissue and thus play a central role in healing processes, for example after injuries to the skin or hair follicle.
Hair root and laser hair removal
The hair root plays a particularly important role in laser hair removal. During laser or IPL treatment, the light is absorbed by the melanin in the hair shaft and in the deep structures of the hair root. The resulting heat energy is concentrated primarily in the hair matrix and the dermal papilla. If these two structures are sufficiently damaged by the heat, neither new keratinocytes nor pigments can form, and hair growth at this site is permanently halted. Since only the active hair roots in the growth phase (anagen) are closely connected to the papilla, they can be effectively destroyed. Therefore, several treatments are necessary to target all hair follicles in the correct cycle stage and achieve a lasting reduction in hair growth.
