Ultrastructure of cranial nerves of rats inoculated with rabies virus.

The V and VII cranial nerves of rats inoculated with rabies virus were studied by electron microscopy. The results were compared with the same cranial nerves of rats inoculated with rabies virus but vaccinated against the disease. The findings are those of axonal degeneration and intense demyelination of the nerves of the group of rats not vaccinated. The vaccinated rats showed some ultrastructural irrelevant alterations when compared with the other group. The degree of ultrastructural alterations found in the group of rats not vaccinated suggests that in rabies severe damage of the cranial nerves occurs and that this may be closely related to the clinical picture of the disease (hydrophobia). Furthermore, as far as the authors know, this has not been considered in the classic descriptions of rabies and it is possible that an immunologic process may take part in the demyelination observed in the present study.