Hair cuticle
The hair cuticle ( cuticle called), and outer cuticle, the outer cortical layer of the hair , and comprising above the other cross- cells , the above hair Mark ( Cortex pilii lie). The 4–5 µm thick cuticle is responsible for protecting the hair from physical and chemical influences (light, cosmetic treatment, etc.). It divides a high cysteine content (25–30%), proteolysis- stable exocuticula and a proteolysis-sensitive endocuticula. It consists of 6–10 such cell layers and is tooth-like connected to the vaginal cuticle - one of the three layers of the inner root sheaths . During hair growth, the hair cuticle and the vaginal cuticle slide together with the inner part of the epithelial root sheath along the outer part to the hair funnel .
By fungi (z. B. Trichophyton rubrum ) or by preparations such as thioglycolic acid derivatives (in permanent wave preparations), and sulfates (in Depilatoren ) there is a resolution (maceration) of the hair cuticle (so-called. Keratolysis ). Therefore, the cuticle is used as an indicator of the health of the hair. In healthy hair, the cuticle lies flat and creates a smooth, translucent surface. The light is optimally reflected and thus gives the hair the healthy shine.
The cuticle is of great importance in forensic and environmental medicine , especially since certain substances, such as heavy metals , can be detected in it in higher concentrations than in the hair cortex. However, cosmetic treatments cause morphological , physical and chemical changes to the hair by damaging the cuticle and cortex, but also to a loss of concentration of stored substances due to instabilities of the molecules against some chemical agents ( hydrogen peroxide , ammonia ) and structural changes in the hair fibers as well as reduced The damaged hair fibers can absorb substances. For example, it has been shown that after bleaching and permanent wave treatment, the concentration of morphine , monoacetylmorphine and cocaine decreases. Nevertheless, the amounts of active ingredient stored can still be clearly demonstrated.
literature
- Wilfried Meyer, Gregor Hülmann, Helga Seger: SEM atlas on the hair cuticle structure of central European mammals. M. & H. Schaper Verlag, 2002, ISBN 3-7944-0200-6 .
- S. Berg: Contributions to the acquisition and evaluation of findings in forensic hair examination. In: International Journal of Legal Medicine. ISSN 0937-9827 , pp. 531-545.
Individual evidence
- ↑ L. Pötsch, G. Skopp: Stability of opiates in hair fibers after exposure to cosmetic treatment. In: Forensic Science International. 81, 1996, pp. 95-102.
- ↑ J. Röhrich, S. Zorntlein, L. Pötsch, G. Skopp, J. Becker: Effect of the shampoo Ultra Clean on drug concentrations in human hair. In: Int. J. Legal Medicine. 113, pp. 102-106.