Neuron/target matching between chorda tympani neurons and taste buds during postnatal rat development

Abstract

During postnatal development, a relationship is established between the size of individual taste buds and number of innervating neurons. To determine whether rearrangement of neurons that innervate taste buds establishes this relationship, we labeled single taste buds at postnatal day 10 (P10) and again at either P15, P20, or P40 with retrograde fluorescent neuronal tracers. The number of single‐ and double‐labeled geniculate ganglion cells was counted, and the respective taste bud volumes were measured for the three groups of rats. The current study replicates findings from an earlier report demonstrating that the larger the taste bud, the more geniculate ganglion cells that innervate it. This relationship between taste bud size and number of innervating neurons is not apparent until P40, when taste bud size reaches maturity. These findings are extended here by demonstrating that the number of neurons that innervate taste buds at P10, when taste bud size is small and relatively homogeneous, predicts the size that the respective taste bud will become at maturity. Moreover, while there is some neural rearrangement of taste bud innervation from P10 to P40, rearrangement does not impact the relationship between taste bud size and innervating neurons. That is, the neurons that maintain contact with taste buds from P10 through P40 accurately predict the mature taste bud size. Therefore, the size of the mature taste bud is determined by P10 and relates to the number of sensory neurons that innervate it at that age and the number of neurons that maintain contact with it throughout the first 40 days of postnatal development. © 2000 John Wiley & Sons, Inc. J Neurobiol 43: 98–106, 2000

Exuberant Neuronal Convergence onto Reduced Taste Bud Targets with Preservation of Neural Specificity in Mice Overexpressing Neurotrophin in the Tongue Epithelium

“…The increased innervation does not "instruct" or "permit" more numerous potential synaptic partners (i.e., in this case, gustducin-expressing receptor cells). Previous study of rat show a correlation between taste bud size and number of innervating geniculate ganglion cells (Krimm and Hill, 2000); bigger buds presumably contain more cells than smaller ones. Surprisingly, in fungiform taste buds in the present system, increased innervation density, per se, is not accompanied by an increased number of putative receptor cells, at least not of those that express gustducin.…”

Induction of ectopic taste buds by SHH reveals the competency and plasticity of adult lingual epithelium

“…In rodents, the size of endogenous taste buds is positively correlated with the number of gustatory neurons providing afferent innervation (Krimm and Hill, 2000). We examined whether PGP9.5 + intragemmal neurite density also correlated with taste bud size.…”

Hedgehog pathway blockade with the cancer drug LDE225 disrupts taste organs and taste sensation

“…hedgehog signaling and taste; taste bud and fungiform papillae; hedgehog pathway inhibitors; cancer drugs and taste sensation; chorda tympani nerve responses TASTE SENSATION ON THE ANTERIOR tongue is relayed via chorda tympani nerve fibers that connect and synapse with receptor cells in taste buds in fungiform papillae and anterior folds of the foliate papillae (Breslin and Spector 2008;Krimm and Hill 2000;Mistretta 1991). Taste buds include 50 -100 differentiated cells spanning the depth of the lingual stratified squamous epithelium (Chaudhari and Roper 2010).…”