Except for the face, eyelids, friction surfaces, and lips, the epidermis of the rhesus monkey contains no discernible melanocytes. After ultraviolet irradiation, however, dopa positive dendritic cells appeared. With daily sequential irradiation, the number of histochemically demonstrable dopa positive dendritic cells peaked after 30 exposures, then declined to a basal level which was maintained for the duration of the experiment (216 exposures or 43 weeks). Pigment cells can be restimulated by shading part of the irradiated area and then reirradiating after 3 months. While shaded, dopa positive cells disappeared; but when reirradiated, they reappeared, increased, then declined again to a basal level. These melanocytes, unlike those in other primates, require high threshold levels of irradiation to produce a response, have a definite period during which they are active, and transfer very little melanin to the surrounding keratinocytes. Long term ultraviolet irradiation has no discernible effect on dermal pigment containing cells.
|Original language||English (US)|
|Number of pages||6|
|Journal||Journal of Investigative Dermatology|
|State||Published - 1975|
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