Sympathetic fibers innervating the extraocular muscles: cells of origin in the cat superior cervical ganglion.

Cells of origin of sympathetic fibers innervating the extraocular muscles were demonstrated in the cat superior cervical ganglion (SCG) using the horseradish peroxidase (HRP) technique. Each injection of HRP into the muscles was confirmed by labeling in the oculomotor, trochlear and abducens nuclei. In all cases retrogradely labeled neurons were found to be distributed widely to the ipsilateral SCG. Labeled neurons were round or oval in shape and majority of these were medium in size. There were some large-sized neurons which frequently showed to have long dendrites expanding rostrocaudally. The labeling was characterized by localization in the rostral two-thirds of the SCG after HRP injections into the medial, lateral and inferior and superior oblique muscles. However, the labeling was found in the whole of the SCG after HRP injections into the superior rectus and inferior oblique muscles. Compared with our previous studies demonstrating cells of origin of the sympathetic fibers in the facial and hypoglossal nerves, the present experiments showed quite different pattern of distribution of labeled neurons in the SCG.