Immuno-electronmicroscopic study on the serotoninergic taste cells and calcitonin gene-related peptide nerve fibers in mouse taste buds / 대한해부학회지

ABSTRACT

To investigate the distribution, ultrastructure and synapsis of serotoninergic cells and CGRP nerve fibers in mammalian taste buds, immunohistochemistry and electronmicroscopy were applied to mice vallate papillae. In normal mice, 1~2 serotonin immunoreactive cells were present in each taste bud section. After preloading 5-HTP, 3~6 cells showed strong immunoreactivity for serotonin. These cells were elongated, and their cytoplasm extended from the taste pore to the base of the taste bud. CGRP nerve fibers formed thick subgemmal nerve plexus under the basal lamina, and branched varicose perigemmal and intragemmal nerve fibers. Under the electron-microscope, three types of taste cells; dark cell, light cell and basal cells, were identified by their shape, location and electrical densities. Immuno-electronmicroscopy revealed that serotoninergic cells were dark cells. CGRP nerve fibers were located in and around taste buds, but the synaptic contacts with taste cells was not found. These findings indicate that mice taste cells are consisted of dark cell, light cell and basal cells, and dark cells contain serotonin. And, CGRP nerve fibers in taste buds may function as general sensory fibers.