[Prion diseases at the present stage and the investigations conducted at the M. P. Chumakov Institute of Poliomyelitis and Viral Encephalitides, Russian Academy of Medical Sciences].

The review deals with the basic characteristics of prion diseases of man and animals. It details the studies of some little known aspects of the pathogenesis of prion diseases and their lifetime diagnosis, conducted at the M. P.

Cytopathological changes in human and animals brains in prion diseases.

Studies of histological preparations of the brains of humans and animals with prion diseases showed that neuron vacuolization often starts and develops intensely in the distal segments of dendrites. Two types of neuron body death were noted - cytolysis and pyknosis, the latter usually being associated with vacuolization of dendrites. The involvement of the main types of neuroglia in the pathogenesis of prion diseases was established, which provides grounds for referring to gliosis rather than astrocytosis.

[Gliosis as a trigger of pathomorphological changes in prion diseases].

Experiments with three cell lines revealed that the scraplecontaining cerebral extract, obtained from preliminarily infected 6-month mice, sharply induced the cellular proliferation, which was registered yet in 3 days after incubation. However, the cerebral extract of healthy 6-month mice did not virtually influence the velocity of cells' reproduction in all three cultures. The authors suggest, with respect to published data and to their independently found research results, that the gliosis of primary importance in shaping up the pathomorphological alterations in the cerebral tissue in prion diseases of man and animal.

[Cytopathological changes in human and animal brain in prion diseases].

The study of brain histological sections of humans and animals afflicted by prion diseases has shown that neuronal vacuolization began in and intensely spread from the distal portions of dendrites. Two types of neuronal cell body death were demonstrated, including cytolysis and pyknosis, the latter being usually associated with dendrite vacuolization. The involvement of major glial types in the pathogenesis of prion diseases was established, which argues against the concept of astrocytosis in favor glyosis.