[The effect of pyrogens on the ultrastructure of the reticular nuclei and large raphe nucleus of the medulla oblongata in the cat].

Investigation of ultrastructure of reticular nuclei in the large nucleus of the raphe medullae oblongatae has revealed a close position of some neurons to the vascular endothelium. Intravenous administration of exo- or endogenic pyrogens produces dilatation of the perivascular space and appearance of lipid phagocytes in it. Simultaneously in neurons, glio- and endotheliocytes lysosomes, lipofuscin and vacuoles are revealed. The changes detected are transitory and not specific for the agents applied.