TY - JOUR
T1 - The spinal nerves innervate putative chemosensory cells in the ventral skin of desert toads, Bufo alvarius
AU - Koyama, Hiromichi
AU - Nagai, Takatoshi
AU - Takeuchi, Hiro aki
AU - Hillyard, Stanley D.
N1 - Funding Information:
This study was supported by the US-Japan Cooperative Science Program from JSPS, by Grants-in-aid for Scientific Research from the Ministry of Education, Science, Sports and Culture, Japan (10640656), and by the Sumitomo Foundation to T.N., and by NSF (IBN-9612053) to S.D.H.
PY - 2001
Y1 - 2001
N2 - 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.
AB - 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.
KW - Chemoreception
KW - Electron microscopy
KW - Fluorescent dye
KW - Salt taste
KW - Toad, Bufo alvarius (Anura)
KW - Water absorption
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U2 - 10.1007/s004410100370
DO - 10.1007/s004410100370
M3 - Article
C2 - 11396713
AN - SCOPUS:0035033960
SN - 0302-766X
VL - 304
SP - 185
EP - 192
JO - Cell and Tissue Research
JF - Cell and Tissue Research
IS - 2
ER -