Abstract

A ganglionated nerve plexus (GNP) found in the nasal vestibular mucosa of the adult musk shrew, and most likely belonging to the nervus terminalis, was studied by electron microscopy. The GNP, which contained ganglion cells and both myelinated and unmyelinated nerve fibers, was located in the subepithelial layer of the mesial vestibular mucosa of the snout processes. The ganglion cells were characterized by an eccentrically located round nucleus, dispersed mitochondria and Golgi apparatuses, and many small vesicles. Nissl bodies were rare. The ganglion cells, solitary or in a small group, were entirely covered with satellite cell sheaths. Semiserial sections suggested that a given ganglion cell directly extends one nerve process and plural modified cilia. There were no synaptic contacts between the ganglion cells and efferent nerve elements. On the other hand, it was seen that the epithelium overlying the GNP contained many nerve terminals which probably originated from the GNP. It is suggested that the ganglion cells in the nasal vestibular GNP of the musk shrew represent primary sensory neurons.