EFFECT OF A SINGLE DOSE OF ULTRAVIOLET RADIATION ON EPIDERMAL MELANOCYTES

[摘要] Skin of man and guinea pigs was exposed to a single dose of 300 m[mu] monochromatic radiation. Quantitative histologic data on melanocyte populations together with histochemical and biochemical observations on changes in tyrosinase activity were collected at various time intervals. No significant increase in the density of melanocyte population was observed; however, there were morphologic changes indicating increased functional activity. Tyrosinase activity was found to be enhanced after 72 hrs. The rate of melanogenesis is more dependent on the functional activity of melanocytes (turnover rate of tyrosinase, formation, melanization and donation of melano-somes) than on a numerical increase of these cells.