The fate of a radio-opaque medium injected into the sciatic nerve.

Considerable controversy exists concerning the relationship between the tissue spaces of the central nervous system and meninges, and those of the remainder of the body. It has been suggested that some materials may reach the central nervous system by routes other than through the hematoencephalic barrier. One suggested pathway is the tissue spaces of peripheral nerves. Other work in this laboratory (4) indicates that tetanus toxin may ascend via this route. It was hoped that the relationship between the tissue spaces of peripheral nerves and the tissue spaces found centrally would be further clarified by determining the course of inert materials injected into peripheral nerves in a number of species of mammals. Consideration was given to radio-opaque media and visual dyes.