Microanatomy of the palatal mucosa of the semiaquatic malayan box turtle, Cuora amboinensis, and functional implications.

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.