Submicroscopical aspects of the melanogenesis and malignant melanomas.

The most important pigment of the human organism is the melanin. After a short representation of the most essential reactions of the biosynthesis of eu- and pheomelanins there are discussed some aspects of the formation of melanosomes as well as exhibited the structure of eumelanosomes and pheomelanosomes. In the tumour cells of the most melanotic malignant melanomas there can be observed clearly either eumelanosomes or pheomelanosomes. Therefore, two types (Type A and Type B) have been distinguished. One typical tumour cell of both types has been characterized ultrastructurally. A retrospective analysis of electron microscopically investigated melanomas which have been ascertained histologically shows that tumours containing eumelanosomes are more frequent than those with pheomelanosomes.