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. Accumulation of phagocytes (microgliocytes, blood macrophages, pericytes) and release of lymphocytes from blood vessels with diffuse infiltration of brain tissues by these cells to form accumulations around degeneratively changed neurons were noted.