Taste disks are induced in the lingual epithelium of salamanders during metamorphosis

Hiro Aki Takeuchi, Shuji Ido, Yu Ichi Kaigawa, Takatoshi Nagai

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Abstract

Morphological changes of oral cavity during metamorphosis with special reference to the taste organ were examined in Ezo salamanders (Hynobius retardatus) and axolotls (Ambystoma mexicanum), and compared with those in bullfrogs (Rana catesbeiana). The non-distensible tongue of salamanders changed the structure progressively during metamorphosis: a small area of the rostrum protruded and developed caudally with recession of the flat area of the tongue. The protrusion that developed on the tongue had numerous papillae, as seen in the frog tongue. The apical region of the papillae occasionally had a cell mass similar to the taste disk of frogs (termed a taste disk-like cell mass). On the flat area of the tongue, the barrel-shaped taste buds of larval salamanders were transformed into taste buds with a wider receptor area. The barrel-shaped taste buds decreased progressively during metamorphosis, while taste disk-like cell masses increased. Neuronal labeling with an antibody to neuron-specific enolase and fluorescent carbocyanine dye showed that the taste disk-like cell masses in metamorphosed salamanders were innervated by the glossopharyngeal nerve (nerve IX). Nerve IX responded to taste stimulation as well as mechanical stimulation applied to the rostral tongue. During metamorphosis the salamanders undergo transformation and rearrangement of taste organs on the tongue possibly as an adaptation to the terrestrial environment.

Original languageEnglish
Pages (from-to)535-545
Number of pages11
JournalChemical Senses
Volume22
Issue number5
DOIs
Publication statusPublished - 1997 Oct 1

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ASJC Scopus subject areas

  • Physiology
  • Sensory Systems
  • Physiology (medical)
  • Behavioral Neuroscience

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