[Problems in the electron microscopic diagnosis of neurosarcomas].

Electron microscopical analysis of 113 cases of neurogenic tumours of the human soft tissues is presented. Ultrastructural signs of neurogenic differentiation are distinguished; neuronal and those of nerve sheaths. The comparison of the ultramorphology of neurosarcomas with that of carcinoids and granular cell tumours is performed.

[Problems of the differential diagnosis and classification of liposarcomas (electron microscopy study)].

Ultrastructure of both liposarcomas of different histological types and those with non-verified diagnosis are studied. Liposarcomas are shown to contain a basic complex of ultrastructural features of lipid differentiation and different histological types of these tumours have, in principle, identical features varying in the degree of their expression. The questions of a differential diagnosis of liposarcomas and other tumours can be successfully solved on the basis of the above findings, and even more, a group of liposarcomas with a severe cataplasia that does not have histological analogues may be distinguished.

[Ultrastructure of human embryonal liposarcoma].

Human embryonal liposarcoma and embryonal fat have been studied histologically, in semithin sections, and electronmicroscopically. Specific ultrastructural features of embryonal liposarcomas allowing them to distinguish from other tumours are as follows: the presence of lipid vacuoles varying in size, number and structure, small mitochondria with dense matrix, specific filamentous apparatus, basal-like material in plasma cell membrane and in the intercellular space cytoplasmic sprouts forming peculiar "pockets" and general cell architectonics. Similarities and differences in the ultrastructure of embryonal liposarcomas and embryonal fat are found.

[Cytoplasmic filaments in the electron microscopy diagnosis of sarcomas].

The ultrastructure of cytoplasmic filamentous material in cells of different human sarcomas was studied and several types of it are distinguished. The first type is specific and can be used as a differential diagnostic marker of tissue appurtenance of neoplasias: in fibroasarcoma cells--a uniform layer of thin filaments located near the plasmic membrane; in rhabdomyosarcomas--thick sheets of long filaments; in leiomyosarcomas--bundles of filaments with focal consolidation; in liposarcomas--loosely packed scarce layers of thin filaments of cylindrical shape; in malignant synoviomas--rod-shaped bundles of thin filaments, endotheliomas--thick single bundles of predominantly perinuclear location. Two types of nonspecific filamentous apparatus in cells of these neoplasias were distinguished: widelooped loose filamentous network and thick circular sheets.