[Sympathetic postganglionic innervation of external carotid artery, internal carotid artery, common carotid artery and aorta in the dog--experimental study using HRP and WGA-HRP].

The sympathetic postganglionic innervation of the external carotid artery, internal carotid artery, common carotid artery (CCA) and aorta was studied by using retrograde axonal transport of the horseradish peroxidase (HRP) and wheat germ agglutinin-HRP conjugates (WGA-HRP). When the powder of HRP was applied to the sheaths of internal and external carotid arteries, labeled cells were found only in the ipsilateral superior cervical ganglion (SCG). After injection of WGA-HRP into the walls of the (1) distal, (2) middle, and (3) proximal parts of the CCA, labeled cells were observed in the following ganglia, respectively; (1) the SCG and middle cervical ganglion (MCG), (2) the SCG, MCG and stellate ganglion (SG), and (3) the MCG and SG. These labeled cells were seen in these ganglia of both sides, but they were more marked ipsilaterally. Following injections of WGA-HRP into the walls of ascending and descending aortae, labeled cells were found in the bilateral MCG and SG. These results suggest that the vasodilation of the head and neck after stellate ganglion block using local anesthetic agents is caused by neuronal block of preganglionic sympathetic fibers passing through the stellate ganglion and terminating in the superior cervical ganglion.