[Electron microscopy demonstration of the myoblastic origin of various tumours]

In the histogenetic classification of spindle-cell tumours, in particular malignant ones, it is an advantage to use electronoptic examination. It proves useful in particular in the diagnosis of tumours of myoblastic origin. Inadequate formol fixation of bioptic material in this group does not matter too much and does not alter diagnostic structures which was proved by four illustrative observations (an angioleiomyoma of the subcutaneous layer, congenital generalised fibromatosis with a muscular component, rhabdomyocellular sarcoma of the urinary bladder, alveolar rhabdomyosarcoma).