Hair Care - DermaAmin

Figure 1.6
The layers of the hair shaft.
Figure 1.7
Hair physiology 7
The organization of the cuticle, cortex,
and medulla.
the proximal edges resting against the cortex (Figure 1.8). 31 The cuticular scales are
arranged much like roofing shingles to provide five to ten overlapping cell layers, each
350–450nm thick, to protect the hair shaft along its entire length. The cell structure of the
cuticle is composed of three major layers: the A-layer, the exocuticle, and the
endocuticle. It is the clear A-layer, which is high in sulfur-containing proteins, that pro
tects the hair from chemical, physical, and environmental insults. 32 A healthy hair shaft is
characterized by an intact, well-organized cuticle (Figure 1.9). It is this unusual structure
of the hair shaft that provides for the unique physical properties of hair. 33