Morphology, and muscle- and papilla-volume ratios, of the tongue of Laudakia stellio (Agamidae, Squamata): A histological and stereological study

Abstract

We examined the histological structure of the tongue of Laudakia stellio, the starred agama lizard (Agamidae, Squamata), under light microscopy. We also investigated the muscle and papilla volume ratios, with volumes of each aspect of interest estimated according to the Cavalieri method. The macroscopically short, thick and muscle-rich front tip of the tongue of L stellio does not show any bifurcation, and under light microscopy, the oval-shaped papilla-free front tip was seen to be covered by keratinized stratified epithelium. The dorsal and ventral parts were different, with the former partially covered by keratinized stratified epithelium and rich in secretory glands and secretory cells. The ventral part, which contained keratinized stratified cells, had a flat surface with no papillae. The dorsal surface of the anterior and posterior parts contained fungiform papillae, with the apical parts of these papillae containing minimal keratin; the inter-papillar space was covered by keratin-free squamous stratified epithelium. The middle section of the tongue contained cylindricaltype papillae, with serous and mucous secretory glands and ducts at their base. Finally, the frontal and middle parts of the ventral and dorsal surfaces did not contain any taste buds, although there were some in the hind part of the dorsal surface. As morphometric estimates of volumes of the muscles and papillae, the mean volume ratios (relative to total tongue volume)±standard deviation were 0.66±0.03 and 0.33±0.03, with mean coefficients of error of 0.02 and 0.03, respectively. © 2007 Zoological Society of Japan.