RESEARCH ARTICLE Morphology and Histology of the Tongue and Oral Chamber of Eublepharis macularius (Squamata: Gekkonidae), with Special Reference to the Foretongue and its Role in Fluid Uptake and Transport Heather A. Jamniczky • Anthony P. Russell • Megan K. Johnson • Ste ´phane J. Montuelle • Vincent L. Bels Received: 16 October 2009 / Accepted: 22 October 2009 Ó Springer Science+Business Media, LLC 2009 Abstract Detailed descriptions of tongue morphology of members of Squamata that refer to functional implications other than food processing are rare. Herein we focus on the morphology of the dorsal epithelium and internal structure of the tongue of the Leopard Gecko, Eublepharis macu- larius, emphasizing the foretongue and its relation to fluid uptake. We employ both scanning electron microscopy and serial histology to examine the morphology of the entire tongue, its component regions, and its situation in the oral chamber. We recognize five distinct morphological regions of the dorsal tongue surface, each of which is distinctive both morphologically and histologically. The foretongue bears papillae quite different in structure and spacing from those of all other tongue regions, and these non-glandular structures are involved in gathering and transporting fluid from the environment. Fluid unloaded from the foretongue in the region of the vomeronasal sinus is channeled through the network of cuboidal papillae and directed towards a pair of compartments lateral to the tongue in which fluid pools during a drinking bout. This allows the dorsal surface of the mid- and hind-tongue, which are involved in food processing and manipulation, to be largely segregated from the pathway of fluid flow. We relate our findings to descriptions of the tongue of other taxa, and propose functional hypotheses for the observed morphology. This study provides new anatomical information upon which future studies of the functional morphology of the buccal apparatus in the Gekkota can be based. Keywords Tongue Á Epithelium Á Histology Á Eublepharis macularius Á Gekkonidae Á Drinking Introduction The morphology of the tongue of members of Squamata is known from a relatively large number of studies (e.g. Seiler 1891, 1892; de Rooij 1915; Camp 1923; Gnanamuthu 1937; Iwasaki and Miyata 1985; Iwasaki et al. 1985; Schwenk 1985, 1986, 2000; Rabinowitz and Tandler 1986; Smith 1986, 1988; Iwasaki 1990, 2002; Delheusy et al. 1994; Toubeau and Bels 1994; Herrel et al. 2005). Inves- tigations of the gross anatomy of the squamate tongue, supplemented by light and electron microscopy, across a broad spectrum of subordinate taxa, have demonstrated considerable morphological variation in the structure of the dorsal lingual epithelium. Much attention has been paid to describing the features of the tongue surface, and the phylogenetic implications of these features have been extensively discussed (e.g. Schwenk 1985; Smith 1988). Several authors have also offered functional explanations for the morphological diversity evident in squamate tongue epithelia (e.g. Beisser et al. 1998, 2004; Schwenk 2000; Iwasaki 2002; Herrel et al. 2005), mostly in relation to adaptations for feeding in a terrestrial environment. H. A. Jamniczky (&) Á A. P. Russell Á M. K. Johnson Vertebrate Morphology and Palaeontology Research Group, Department of Biological Sciences, University of Calgary, 2500 University Drive NW, Calgary, AB T2N 1N4, Canada e-mail: hajamnic@ucalgary.ca Present Address: H. A. Jamniczky Department of Cell Biology and Anatomy, Faculty of Medicine, University of Calgary, 3330 Hospital Drive NW, Calgary, AB T2N 4N1, Canada S. J. Montuelle Á V. L. Bels Muse ´um National d’Histoire Naturelle, USM 302, 75005 Paris, France 123 Evol Biol DOI 10.1007/s11692-009-9072-9