Showing papers by "Charité published in 1972"

Ultrastructural differences in human malignant melanomata. An electron microscopical study.

Abstract: Summary.— Thirty-two human malignant melanomata have been investigated with the electron microscope. On the basis of the fine structure of the melano-mata and melanosomes we have distinguished 2 different tumour forms (Type A and Type B). The melanosomes of Type A appear cigar-shaped, whereas the premelanosomes have an internal helical structure exhibiting periodicity. Most of the mitochondria of this tumour type show an elongated from and numerous cristae. The nucleolus is usually very large and exhibits some vacuole-like structures which contain a fine granular substance. The nucleus is distinguished by the different extent of heteropyknotic chromatin and fre-quently has “nuclear bodies”. The tumour cells of the other melanoma form (Type B) contain only spherical melanosomes, whereas the premelanosomes show no internal fibrillar structure. The mitochondria mostly appear spherical as well; their matrix is slightly electron dense. There is no marked difference between the nuclei of these 2 melanoma forms. Their pathogenesis is discussed.