Neurocalcin-immunoreactive neurons in the petrosal ganglion innervate the taste bud

The distribution and origin of neurocalcin-immunoreactive (NC-ir) nerve fibers in the taste bud and carotid body were examined by an immunofluorescence method. In the circumvallate papilla of the tongue, NC-ir nerve fibers made subepithelial nerve plexuses and occasionally penetrated the taste bud. However, the carotid body was devoid of ir nerve fibers. In the petrosal ganglion, 32% of neurons were immunoreactive for NC. Such neurons were mostly medium-sized to large, and scattered throughout the ganglion. In the superior cervical and intralingual ganglia, numerous ir varicose fibers surrounded postsynaptic neurons. However, NC-ir could not be detected in cell bodies of these neurons. The retrograde tracing method indicated that NC-ir petrosal neurons innervated taste buds in the circumvallate papilla. NC-ir neurons may have a gustatory function in the petrosal ganglion.