Axonal transport studies of the trigeminal nerve roots of the cat. With special reference to afferent contributions to the portio minor.

The transport of protein molecules by axoplasmic flow has been used to trace axonal projections in the trigeminal system of the cat. Autoradiography with tritiated amino acid labeling of synthesized proteins and the transport of the enzyme horseradish peroxidase have been employed. The latter method has enabled demonstration of afferent axons within the portio minor, some of which are of cutaneous origin. The trigeminal "motor root" thus appears to be homologous with spinal ventral roots in possessing a potentially significant sensory function. The presence of such afferent fibers in nerve roots thought previously to have an exclusively motor function may explain instances of preserved sensation or failure to relieve pain following rhizotomy of the trigeminal portio major.