Brainstem connections of vagal afferent nerves in the ferret: an autoradiographic study

Using an autoradiographic technique the central connections of vagal afferent fibres in the ferret were studied. The results show that the principal site of termination is the ipsilateral nucleus of the tractus solitarius with smaller projections to the contralateral tractus nucleus, the dorsal motor nucleus of the vagus and the area postrema and subpostrema. The fibres cross the midline via the commissural nucleus of Cajal. No evidence of vagal afferent fibres was found in the reticular formation, the spinal tract of the trigeminal nerve, the external cuneate nucleus or the dorsal horns of the first and second cervical spinal segments. The findings from all studies using axon tracing techniques on vagal afferent fibres are summarised.