[A contribution to the ultrastructure of malignant melanomas of the iris (author's transl)].

After a short description of clinical facts, electron microscopic findings on four malignant melanomas of the iris are described. Though all tumors had been classified as being of the spindle cell type, the ultrastructure of the tumor cells shows remarkable differences between the four cases. This can be seen especially by comparison of the nucleoli, the chromatin, and the cytoplasmatic structures. All four tumors have the same spherical type of melanosomes. No morphologic features pointing to relative clinical harmlessness of iris melanomas were found.