Chondroma of the bony external auditory canal attached to the short process of the malleus.

A chondroma located in the external auditory canal is a rare finding. Here, we report the case of a 12-year-old girl who attended our clinic with complaints of a rustling sound in her left ear. Otoscopic examination revealed a tiny bone-like tumor protruding from the anterior wall of the bony external auditory canal, attached to the short process of the malleus. An audiogram revealed a conductive hearing loss in her left ear, although she did not notice it. After excision of the tumor through the ear canal, her complaints disappeared and her hearing recovered. Histologically, the tumor proved to be a chondroma.

Ganglion cells in the posterior cricoarytenoid muscle of the rat following experimental denervation.

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 approximately 50 nm in diameter and several dense-cored vesicles approximately 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.

The distribution of ganglion cells in the posterior cricoarytenoid muscle of the normal adult rat. A light and electron microscopic study.

We employed by light and electron microscopy to examine the innervation of the posterior cricoarytenoid muscle of the adult rat. The laryngeal nerve was found to often bifurcate into two different bundles. One contained large myelinated (motor) nerve fibers, which were located along the frontal (ventral) muscle surface and entered the muscle at its middle portion to form neuromuscular contacts with individual muscle fibers. The other nerve bundle consisting of clustered ganglion cells (20-30 microm in diameter) and their associated nonmyelinated and small-sized myelinated nerve fibers were mainly found on the dorsal side of the muscle and often ran along the peripheral clefts or depressions of the muscle surface. The nerve bundle often extended side branches, which entered the muscle to be distributed among muscle fibers and near arterioles. Some ganglion cells are considered to enter the muscle, accompanied by branched nerves. Intramuscular ganglion cells and their associated nerve fibers examined by electron microscopy were similar in fine structure to perimuscular ganglion cells and their associated nerve fibers. Nerve fibers contained abundant clear synaptic vesicles which were cholinergic in nature, and often formed synapses with both neighboring axons and the cell body of the ganglion cells. These findings suggest that, in the rat posterior cricoarytenoid muscle, perimuscular and intramuscular ganglion cells exist and may be involved in innervating and contracting smooth muscle cells of the arterioles, thus regulating the blood flow or intravascular pressure.