Development of Gustatory Organs and Innervating Sensory Ganglia

Abstract

Taste function requires neural circuits to transmit gustatory infor-mation from taste receptor cells in taste buds, via afferent nerves tothe soma of ganglion neurons, and through central ganglion proc-esses into the brainstem. During initial formation, the sensoryganglion neurons have a key situation in establishing receptive fieldsby extending neurites bidirectionally, to the peripheral taste organsand to central taste nuclei.Our laboratory is studying functional differentiation of sensoryganglia that innervate the tongue, and morphogenesis andpatterning of the tongue and papilla organs. The lingual ganglia andtaste papillae initially develop independently, but then becomereciprocally dependent as ganglia derive molecular support fromgustatory papillae and the papillae require sensory innervation forgrowth and morphogenesis (Mistretta, 1998). Currently our focus ison the geniculate and trigeminal ganglia, which innervate anteriortongue, and the fungiform papilla taste organs innervated by theseganglia. Geniculate and trigeminal ganglia innervate spatiallycontiguous, but functionally distinct, sensory organs of the fungi-form papilla: the trigeminal neurons innervate lateral papilla epithe-lium and subserve somatosensation and nociception, whereas thegeniculate axons project to central apical papilla epithelium to inner-vate cells that will form taste buds for gustatory sensation (Mistrettaand Hill, 2003).In this brief paper we summarize some recent work on develop-ment of tongue and taste regions, and on early functional pheno-types of the geniculate and trigeminal ganglia.