The spinal nerves innervate putative chemosensory cells in the ventral skin of desert toads, Bufo alvarius

Hiromichi Koyama, Takatoshi Nagai, Hiro aki Takeuchi, Stanley D. Hillyard

Research output: Contribution to journalArticlepeer-review

13 Citations (Scopus)


Toads normally obtain water by absorption across their skin from osmotically dilute sources. When hyperosmotic salt solutions are presented as a hydration source to dehydrated desert toads, they place the ventral skin onto the source but soon afterwards escape to avoid dehydration. The escape behavior coincides with neural excitation of the spinal nerves that innervate putative chemosensory cells in the ventral skin. In the present study, fluorescent dye translocated through the spinal nerves to those receptor cells in the epidermis was photoconverted in the presence of 3,3′-diaminobenzidine tetrahydrochloride for electron-microscopic observation of the cells and associated nerve terminals. Most of the photoconverted cells were located in the deepest layer of the epidermis, with some being in more intermediate layers. No labeled cell was seen in the outermost layer of living cells. In desert toads, flask cells and Merkel cells are occasionally seen in the epidermis. An association of nerve fibers with these epidermal cells has been reported in some species of the anurans. In the present study, however, the cytological features of the photoconverted cells are neither reminiscent of flask cells nor Merkel cells, but are similar to those of surrounding epithelial cells in each layer of the epidermis. We hypothesize a sensory function for these cells, because they have a close association with nerve fibers and participate in the transepithelial transport of salts that must pass through all cell layers of the skin.

Original languageEnglish
Pages (from-to)185-192
Number of pages8
JournalCell and Tissue Research
Issue number2
Publication statusPublished - 2001
Externally publishedYes


  • Chemoreception
  • Electron microscopy
  • Fluorescent dye
  • Salt taste
  • Toad, Bufo alvarius (Anura)
  • Water absorption

ASJC Scopus subject areas

  • Pathology and Forensic Medicine
  • Histology
  • Cell Biology


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