Morphological alterations of epidermal melanocytes in photoageing: an ultrastructural and cytomorphometric study.

To examine pathological changes of melanocytes in photodamaged skin, we performed a comparative cytomorphometric analysis and a qualitative observation of melanocytes from sun-exposed and sun-protected facial skin at the electron microscopic level. The characteristic ultrastructural features of melanocytes in photodamaged skin included a statistically significant increase in their number, a marked nuclear heterogeneity, signs of cell activation, close apposition to photodamaged degenerate keratinocytes, degenerative changes represented by large intracytoplasmic vacuoles, and frequent direct contacts with Langerhans cells. Cytomorphometric analysis revealed significant decreases in cell and nuclear sizes, increases in cell and nuclear perimeters accompanied by irregular contours, and higher degrees of nuclear ellipticity in sun-exposed melanocytes. This study demonstrates that there are remarkable differences in the morphology of melanocytes between photoaged and intrinsically aged facial skin, and supports the concept that photoageing processes contribute to cytological alterations in melanocytes.