The vagal connection of the carotid sinus

We applied wheat germ agglutinin-horseradish peroxidase (WGA-HRP) to the adventitia of the left carotid sinus of cats after tying the glossopharyngeal and the carotid sinus nerves. Forty-five to 255 neurons were labeled in the rostral pole of the nodose ganglion, through the pharyngeal branch of the vagus nerve. Transganglionic label was present only in the ipsilateral dorsal and medial subnuclei of the nucleus tractus solitarii at levels nearly rostral to the area postrema. These findings show the existence of a novel pathway from the carotid sinus, projecting via the vagus nerve, to the nucleus tractus solitarii.