Microanatomy of the Palatal Mucosa of the Semiaquatic Malayan Box Turtle, Cuora amboinensis, and Functional Implications

Abstract

Scanning Electron Microscopy (SEM) revealed that the palate of Cuora amboinensis has a flat surface with keratinized and non-keratinized regions. Keratinization is reflected in disc-shaped keratinized dead cells with rough microplicae on the surface, and is concentrated close to the rhamphotheca. The surface of the non-keratinized hexagonal epithelial cells is dotted with microvilli and sometimes with cilia. Taste buds are present both in lightly keratinized and non-keratinized regions and exhibit a crater-like shape. Light microscopy shows the different tissue layers of the oral mucosa and the different epithelial structures. In keratinized regions, keratinocytes mature from basal to superficial, where they build up keratin layers of varying thickness. In non-keratinized regions, the epithelial cells are arranged in a stratified fashion, and cuboidal to cylindric cells form a superficial layer. Goblet cells appear to be diffusely distributed, but are often organized in goblet cell fields which can be folded into crypts. Taste buds consist of slender epithelial cells, exhibit the typical barrel-like shape and are specially concentrated in the anterior, praechoanal palate. This anterior concentration of taste buds is shown by kinematographic analysis to correlate with the food prehension mode in Cuora amboinensis. The lamina propria of the palatal mucosa consists of loose connective tissue with inflammatory cells between capillaries. All these structures of the oral mucosa act as a functional entity and help determine how successfully an organism adapts ecologically to the environment. Anat Rec,

Oropharyngeal morphology in the basal tortoise Manouria emys emys with comments on form and function of the testudinid tongue

“…Turtles show a great diversity regarding their ecology, they span the range from fully aquatic to fully terrestrial, with a rich range of intermediate variations. This diversity is largely congruent with phylogeny and is reflected in structural specializations of the oropharynx (Winokur,1988; Weisgram et al,1989; Iwasaki,2002; Iwasaki et al,1996a, b; Beisser et al,1995, 1998, 2001, 2004; Heiss et al,2008). The family Testudinidae is the only turtle clade known to exclusively contain true terrestrial forms (Pritchard,1979; Bonin et al,2006; Bels et al,2008).…”

“…Feeding is crucial for survival, and the contribution of feeding systems to fitness is without any doubt substantial (Schwenk and Wagner,2001). Studies on aquatic and terrestrial turtles showed a correlation between phylogeny, feeding mode, and oropharyngeal morphology (Winokur,1973; Weisgram et al,1989; Iwasaki et al,1996a, b; Lemell et al,2000, 2002; Beisser et al,2004; Richter et al,2007; Heiss et al,2008; Natchev et al,2009). Purely aquatic (nonmarine) turtles have a smooth oral surface, poorly developed oropharyngeal glands, a flat palate, and a tiny tongue (Bramble and Wake,1985; Winokur,1988; Weisgram et al,1989; Beisser et al,1995, 1998, 2001; Lemell and Weisgram,1997; Lemell et al,2000, 2002, 2010).…”

Analysis of prey capture and food transport kinematics in two Asian box turtles, Cuora amboinensis and Cuora flavomarginata (Chelonia, Geoemydidae), with emphasis on terrestrial feeding patterns

“…The trochlear process is formed only by the quadrate bones. The palate is flat in C. amboinensis but concave in C. flavomarginata (see also Heiss et al, 2008). The palatines are bright bony plates, they are robust in the Malayan box turtle but thin and transparent in C. flavomarginata.…”

Aquatic feeding in a terrestrial turtle: a functional-morphological study of the feeding apparatus in the Indochinese box turtle Cuora galbinifrons (Testudines, Geoemydidae)

“…Thus, several chelonian species can capture the food on land, but to continue the feeding process they have to go under water (Bramble and Wake 1985;Weisgram 1985;Lemell and Weisgram 1997). Within the largest recent turtle group-Testudinoidea-one can distinguish fully aquatic and completely terrestrial forms, as well as species with amphibious live mode (for overview see Heiss et al 2008;Natchev et al 2009). Some emydid and geoemydid species can handle the diVerent requirements connected to the high density and viscosity of water compared to air (Gans 1969), they can complete the whole feeding process both on land and in water (Summers et al 1998;Natchev et al 2009).…”