| Abstract: | Objective —To investigate morphological changes of the i.m. ganglion cells in the posterior cricoarytenoid (PCA) muscle of the rat following denervation of the recurrent laryngeal nerve. Material and Methods —The recurrent laryngeal nerve on the left side of the rat was resected. Three weeks after transection, the PCA muscle was removed for morphological study using light and electron microscopy. Results —No morphological changes were found in the i.m. ganglion cells in the PCA muscle, even though the myelinated nerve fibers were destroyed and had disappeared in ramified i.m. bundles. Around the cell body, numerous non-myelinated nerve fibers were found; these contained a large number of clear, spherical synaptic vesicles ≈50 nm in diameter and several dense-cored vesicles ≈100 nm in diameter. In contrast, neuromuscular junctions in most muscle fibers with partially disoriented and/or disintegrated myofibrils showed degenerative figures. In some instances, however, multiple nerve terminals were detected in contact with the postsynaptic membrane. Like the varicose swellings of non-myelinated nerve fibers around the ganglion cell body, these nerve terminals contained, in addition to clear synaptic vesicles (50 nm in diameter), several dense-cored vesicles (100 nm in diameter). Conclusion —We suggest that i.m. ganglion cells in the rat PCA muscle may supply postganglionic nerve fibers to the denervated neuromuscular junctions after transection of the nerve. |
