A qualitative ultrastructural study of melanocytes after grenz-ray and UVA irradiation.

Seven female human subjects were irradiated with 4 Gy of grenz rays and 30J/cm2 of long-wave ultraviolet (UVA) radiation once a week for three weeks. 6/7 subjects when irradiated on the back developed a clearly visible pigmentation due to both grenz-ray and UVA pigmentation. The effect on epidermal melanocytes was observed with transmission electron microscopy. Ultrastructural changes in melanocytes following both grenz-ray and UVA irradiation were an increase in the number of premature and mature melanosomes, elongation and protrusion of cytoplasm, sometimes indented nuclei, and the development of multilamella of basal lamina. Compared with UVA-irradiated skin, in the same individuals the melanocytes seemed somewhat more hypertrophic after grenz-ray irradiation. In general the observed qualitative ultrastructural differences between UVA- and grenz-ray-irradiated melanocytes were limited, indicating that the influence of grenz-rays is similar to that of UVA.