[Determining aging changes of melanin granules of human scalp hairs by image analyser]

Using electron micrographs of human hairs, we measured the minor axis and density of hair melanin granules in a 0 year old infant, 20-30 year old adult and 60-70 year old adult by an image analyser for the purpose of determining the aging changes of melanin granules of human scalp hairs. The melanin density of the outer hair cortex was higher than that of the inner hair cortex. There were no differences between the 0 year old infant and the 20-30 year old adult in the minor axis and density of melanin granules, but significant differences were evident in the minor axis between the 60-70 year old adult and the other generations. Significant differences were noted in the density of melanin granules of the inner hair cortex between the 60-70 year old adult and the other generations. As a result of the quantitative analyses, it was proved that the melanin granules of human scalp hair increase in size and decrease in number by age.