ULTRASTRUCTURE OF THE GANGLION ON HUMAN INTERNAL LARYNGEAL NERVE

There is now definite evidence for the presence of a macroscopic gangl ion on the human internal laryngeal nerve, with the distribution of it s post-ganglionic fibres to the glands in the saccule and to the gland s at the root of epiglottis in the vicinity of the opening of the,sacc ule. This ganglion could be identified as early as 14 weeks in human f oetal larynx, which contains immature neurons. Seven ganglia, dissecte d from human laryngectomy specimens and resected for carcinoma larynx, were studied by electron microscopy. Ultrastructurally, the neurons a nd the synaptic terminals had both small, round, luscent vesicles and dense core vesicles. Symmetrical, asymmetrical and electrical synaptic complexes were noted. A few neurons revealed degenerative changes sug gestive of axotomy. The location of the ganglion on the internal laryn geal nerve, a branch of nervus vagus, and ultrastructural demonstratio n of large and small dense core vesicles and small luscent vesicles in the neurons of this ganglion, lead us to believe that the ganglion is parasympathetic in nature.