External, or visible, part called Stem or Shaft. It has a long, thin cylinder shape formed by overlapping cells, tied together and made up of three layers:

• The Midolla: the internal layer, or the “soul” of the hair. It has a spongy consistency and is formed by a number of cells placed one beside the other, in rows separated by air spaces.
• The Cortex: the second layer made up of cells containing keratin and melanin, the pigment that gives colour to the hair.
• The Cuticle: the external, visible, layer consisting in a layer of scale shaped cells, made up of keratin. The cuticle has the function of covering and protecting the internal layers. A healthy cuticle has compact scales and consequently the hair is shiny and soft to touch.

Internal part, placed in a cavity called hair follicle or pilo-sebaceous follicle made up of:

• The Root: the portion of hair “immersed” into the superior part of the follicle.
• The Bulb: the deepest part of the hair follicle with an enlarged ovoid shape. All the germinate activity leading to the construction of the hair structure has its headquarters here.
• The Matrix or the Papilla: the vital zone at the base of the bulb. The papilla, in fact, rich in blood vessels that bring oxygen and nourishment to the bulb, reproduces the germinal cells that develop keratin, they progressively harden and model the different structural parts of the hair (cuticle, cortex and midolla). Immediately above the matrix cells we find melanocytes that produce melanin, the pigment that determines hair colour.
• The Sebaceous Gland: located beside the follicle, it produces sebum, a fatty substance that nourishes and lubricates the scales to give shine and elasticity to hair. Furthermore, the sebum contributes to the formation of the hydro-lipidic film, an aqueous emulsion in oil that protects the cutaneous surface from external aggressions.
• The Pilo-erector Muscle: makes the hair stand up.

Health and beauty of hair are directly dependent on the functional state of the hair follicle and the microcirculation system of the dermal layer.