Ultrastructural comparison between the tongue of two reptilian species endemic in Egyptian fauna; Bosc's fringe-toed lizard Acanthodactylus boskianus and Sinai fan-fingered gecko Ptyodactylus guttatus.

The current observations focused on the ultrastructure comparison between the tongue of two reptile species endemic the Egyptian fauna; Bosc's fringe-toed lizard Acanthodactylus boskianus and Sinai fan-fingered gecko Ptyodactylus guttatus to exhibit the relationship between the lingual epithelium and its function according to their specific feeding strategy. A. boskianus possessed triangular elongated tongue with bifurcated tapering apex and wide base while; the P. guttatus had a triangular flattened tongue with conical shallow bifurcated apex and broad base. The ventral surface of the lingual apex of A. boskianus had transverse while in P. guttatus had two oval pads and median ventral groove. Both surfaces of the tongue of both examined species are covered by stratified squamous epithelium with great variability of degree of keratinization. The dorsal epithelium formed flattened and conical filiform papillae in A. boskianus, while in P. guttatus formed cylindrical papillae, conical, and tall filiform ones. Few taste buds are observed on the fore-tongue but increase on the mid-tongue of A. boskianus, while in P. guttatus, numerous taste buds are distributed on the fore-tongue and mid-tongue. Both surfaces of the laryngeal mound of both examined species provided with numerous of cilia and orifices of laryngeal gland. The present results confirmed that the tongue of A. boskianus acts as a chemoreceptor organ to follow pheromone trails of prey and mates. While in P. guttatus the tongue may play an important role in the feeding mechanism and act as a chemoreceptor organ.