Chemoreceptive and mechanoreceptive paraneurons in the tongue.

Chemoreceptive and mechanoreceptive paraneurons in the tongue include gustatory cells and basal cells of the taste buds, Merkel cells in the lingual epithelium and Merkel or Grandry corpuscles in avian subepithelial connective tissue. Neuron-specific enolase immunoreactivity is recognized in the basal cells, a type of Merkel cells, in the taste buds of teleost fishes and amphibia, certain taste bud cells of mammals and the Merkel cells in birds. The present study also concerns itself with the ultrastructural features of the gustatory cells of the rabbit taste buds, and the Merkel cells of the finch tongue. The functional significance of the dense-cored granules in the gustatory cell is still enigmatic. On the other hand, the dense-cored granules in the Merkel cells may have dual functions storing both neurotransmitters and local hormones. Shortly after giving a mechanical stimulus to the finch tongue, we could demonstrate massive exocytotic changes of the Merkel cell granules.