Distribution of carotid sinus nerve afferent fibers to solitary tract nuclei of the cat using transganglionic transport of horseradish peroxidase.

The distribution of carotid sinus nerve (CSN) afferent fibers to the solitary tract and its various nuclei has been determined using transganglionic transport of horseradish peroxidase (HRP). The ipsilateral solitary tract was labeled and, in addition, the heaviest labeling was seen dorsomedial within the medial solitary nucleus, as well as just lateral to the tractus solitarius in the lateral solitary nucleus. Bilateral labeling was present caudal to the obex in both the medial and commissural nuclei. The paucity of reaction product within the ventrolateral solitary nucleus supports previous neurophysiological studies suggesting carotid chemoreceptors do not make monosynaptic contacts with respiratory neurons within that nucleus.