Sympathetic innervation of the tongue in rats

We employed a glyoxylic catecholaminergic histofluorescence method to study the sympathetic innervation present in the rat tongue. One percent neutral red was used as a counterstain. Many noradrenergic fibers were demonstrated around the blood vessels, muscles, glands and submucosa of the tongue, but not in the epithelium or papilla. In a group of rats following neurectomy, the superior cervical ganglia (SCG) were removed unilaterally or bilaterally. Changes in sympathetic innervation of the tongue were examined 14 days after SCG ganglionectomy. In those animals after unilateral SCG ganglionectomy, we found no noradrenergic histofluorescence in the ipsilateral anterior 2/3 of the tongue, although some scant fluorescence was found in the ipsilateral posterior 1/3 of the tongue. However, no noradrenergic histofluorescence could be observed in animal's bilateral SCG ganglionectomies. Our results indicate that sympathetic innervation of the tongue in rats originates in the SCG, with some cross-innervation of the sympathetic fibers occurring in the posterior 1/3 of the tongue.