Hair structure

Cuticle

Cuticle has approximately 8-10 layers of outermost protective, overlapping flat cells. There are no pigment in cuticle dead cells. Its usually colorless, transparent cells point towards the hair end. Ceramide, like cement, is found in between the scales. It holds the cuticles in position. Chemical solutions used during perming, straightening and coloring can raise these scales so that solutions can enter into the hair shaft. It is this layer which primarily determines how much and how fast chemicals are allowed into the hair to be processed.

Cortex

The cortex is the middle of the most important layer that forms the bulk of the hair. It is this part of the hair that gives strength and elasticity.The cortex can be damaged by strong developer, perm lotion or straightening cream. Fine hair can be damaged easier than coarse hair. Protein and color pigments are found here. Hair color, light or dark, depends upon the amount of grains of melanin present in the cortex. Grey hair is due mainly to the absence of pigment in the cortical layer at the hair bulb.

Medulla

Medulla is known as the pith or marrow of hair shaft. Found in the innermost later or center of hair. It consists of very soft keratin round cells interspersed with air spaces. It is an additional deepest later in coarse hair, it is believed that it carries nutrients and other substances to the cortex and cuticle. This could explain why hair is so affected so rapidly by changes in health. The medulla may be absent in fine or very fine hair.