Innervation of the superior tarsal (Müller's) muscle in the cynomolgus monkey: a retrograde tracing study.

PURPOSE The retrograde transport of wheat germ agglutinin-horseradish peroxidase (WGA/HRP) was used to study the localization of the neurons that innervate the superior tarsal muscle in the cynomolgus monkey. METHODS A 5-10% WGA-HRP solution was applied to the medial part of the superior tarsal muscle. Seventy-two hours later, the animals were killed and perfused with fixative. RESULTS The WGA-HRP-labeled neurons were localized in the ipsilateral trigeminal ganglion, the ipsilateral pterygopalatine ganglion, and the ipsilateral superior cervical ganglion. The labeled somata of the sensory neurons were all found in the ophthalmic ganglionic part and the ophthalmic nerve part of the ipsilateral trigeminal ganglion. Most of the labeled somata were distributed somatotopically in the dorsal region of the ophthalmic part of the ganglion. The labeled somata of the sympathetic neurons were all located in the ipsilateral superior cervical ganglion. Most of these labeled somata, which were distributed somatotopically, were found in the cranial part of the ganglion. The labeled somata of the parasympathetic neurons were all located in the ipsilateral pterygopalatine ganglion, particularly in the central ovoid part of the ganglion. No labeled neurons were detected in the ipsilateral parasympathetic ciliary ganglion, the ipsilateral nodose ganglion, or the first three ipsilateral sensory spinal ganglia; labeled somata could not be detected in any of the contralateral ganglia examined. CONCLUSIONS A complete documentation of all projections of the superior tarsal muscle in the monkey has been presented, and convincing data has been given about the parasympathetic innervation of Müller's muscle.