الفهرس 
Anatomy of hair follicleOnly 14 pages are availabe for public view
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Abstract
Background :Hair graying is one of the prototypical signs of human aging Until now, the exact cause of HG and its treatmet are not identified clearly.
Aim of the work:The aim of this work is to assess the role of melanocortin-1 receptor gene expression and catalase enzyme antioxidant activity and tyrosinase enzyme activity in hair bulbs and shafts and to highlight the interaction of environmental and genetic factors in hair graying.
Subjects and Methods: McR1 gene expression,Tyrosinase and Catalase enzymes activities were measured in 3 groups of patients; group (A) patients with premature hair graying (PHG)<25 years, group (B) individuals with gray hair >40 years, and group (C) control individuals with pigmented hair <25 years.
Results: Mean ranks of the expression of Mc1R gene and Tyrosinase enzyme activity were significantly higher in non-exposed hair bulbs than in exposed ones in all individuals but Catalase enzyme activity was higher in non exposed area than exposed one in group (C) with significant difference but in group (B) and group (A) it was significantly higher in exposed areas than those non-exposed ones Conclusion:Mc-1 gene expression and tyrosinase activity were reduced in association of increased catalase activity in grey hair.