CHARACTERIZATION OF MELANOSOMES AND MELANOGENESIS IN CELLS CULTURED FROM OTAS-NEVUS

Cells from dermis and epidermis of Ota's nevus lesions were cultured t o obtain the pigment producing cells thar are specific epidermal and d ermal melanocytes of nevus Ota. The following media were used: Eagle's minimum essential medium, fortified or not fortified with cholera tox in and phorbol ester. Both epidermal melanocytes and dermal melanocyte s grew in the Eagle's minimum essential medium fortified with cholera toxin and phorbol ester. The melanocytes were characterized by C-14-ty rosine uptake and by identification of melanosomes and status of melan ogenesis in comparison with those reported in dysplastic nevi and mela nomas, as well as those found in Ota's nevus tissue in situ. Eumelanos omes, pheomelanosomes and secondary lysosomal melanosomes appeared in epidermal melanocytes. Pheomelanosomes and melanolysosomes, or myelino siderosomes appeared predominantly in the dermal melanocytes. These me lanosomes seemed to be related to the peculiar skin color of nevus Ota . Some of the abnormal types of melanosomes were very similar to those found in dysplastic nevi and melanomas.