Carcinoma in situ of the testis. Some ultrastructural characteristics of germ cells.

The two cytoplasmic organelles, dense-cored vesicles and "nuages" have been considered to allow positive identification of primordial germ cells in rodents, but no use of these potential markers has been applied to human material. We have observed dense-cored vesicles and "nuages" in the abnormal germ cells of carcinoma in situ of the testis and thus brought further evidence for the germ cell origin of this lesion. These organelles may be useful cytoplasmic markers in the study of germ cell tumors.