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Hair Care - DermaAmin

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1<br />

<strong>Hair</strong> physiology<br />

HAIR STRUCTURE AND EMBRYOLOGY<br />

<strong>Hair</strong> contributes significantly to the visual image of both males and females of all ages.<br />

Every visible major body surface is covered with some type of hair, providing the<br />

creation of endless opportunities for cosmetic adornment. <strong>Hair</strong> is nonliving, yet is<br />

immersed in a cycle of constant renewal and shedding. Unlike vital organs, such as the<br />

heart, liver, or kidneys, where limited cellular renewal can occur, hair growth occurs at<br />

the amazing rate of 0.35mm/day allowing the removal of old, damaged hair that is readily<br />

replaced with new regrowth. 1 <strong>Hair</strong> is the only body structure that is completely renewable<br />

without scarring, as long as the follicle remains a functioning unit. For this reason, the<br />

hair can be subjected to insults that could not be sustained by any other body organ. This<br />

constant renewal also means that induced cosmetic alterations in shape, color, or texture<br />

are temporary until the chemically altered hair is sloughed or trimmed 2 (Figure 1.1).<br />

The hair is a body structure readily accessible for scientific observation, yet much<br />

remains to be understood regarding its growth and regulation. The first dermatologist to<br />

encourage study of the hair was P.G.Unna of Hamburg in 1876. 3 One of Unna’s students,<br />

Martin Engman (Professor of Dermatology, Washington University, St Louis), became<br />

interested in the embryology and development of the hair follicle. His work was furthered<br />

by C.H.Danforth, Mildred Trotter, and L.D.Cady, who published the foundation work on<br />

hair formation in 1925. 4<br />

Figure 1.1<br />

The appearance of the cut end of a<br />

solitary hair shaft.

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