Summary
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1.
Lingual salt glands, secreting hyperosmotic Na/K solutions in response to methacholine, are present inCrocodylus acutus andC. johnstoni but apparently absent from the alligatorids,Alligator mississipiensis andCaiman crocodilus.
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2.
Both secretory rates (6–20 μmol/100 g·h) and concentrations (450–600 mM Na) of glandular secretions are essentially identical in the marine/estuarineC. acutus andC. porosus and significantly higher than in the freshwaterC. johnstoni (1–2 μmol/100 g·h; 320–420 mM Na).
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3.
Lingual glands inAlligator secrete isosmotic Na/K at low rates (1–2 μmol/100 g·h) while those ofCaiman show no response to methacholine.
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4.
The physiological contrast between alligatorids and crocodylids is reflected in distinct differences in the superficial appearance of the tongue and lingual pores.
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5.
It is postulated that the alligatorid condition of low secretory capacity and isosmotic secretion reflects the primitive salivary function of lingual glands from which the salt-secreting capability in crocodylids was derived.
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Taplin, L.E., Grigg, G.C., Harlow, P. et al. Lingual salt glands inCrocodylus acutus andC. johnstoni and their absence fromAlligator mississipiensis andCaiman crocodilus . J Comp Physiol B 149, 43–47 (1982). https://doi.org/10.1007/BF00735713
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DOI: https://doi.org/10.1007/BF00735713