Histo-Morphological Comparison of the Tongue between Grainivorous and Insectivorous Birds.

The study aimed to illustrate the influence of feeding habits in the anatomical feature and histological structure as well as some histochemical observations on the tongue of two species of birds which differ in their classification, activity and habitat as; The domestic pigeon, Grainivorous bird, and cattle egret, Insectivorous bird, using light and SEM studies. Results showed that the tongue of two species was differing in size, shape and structure. The tongue of pigeon appeared short and triangular; while in cattle egret was long lanceolate in shape with narrow tapering apex. Dorsal large conical lingual papillae presented between the body and the root of both tongue of the studied birds. They were arranged in form of U-letter in pigeon and in form of wide V-letter in cattle egret. Histologically, both dorsal and ventral lingual surfaces lined with keratinized stratified squamous epithelium, which decreased in the thickness and the degree of keratinization toward the base. The dorsum of the apex of pigeon tongue showed desquamated epithelial cells with filiform papillae, these papillae not observed in the egret¢s tongue. The tongue of cattle egret contained longitudinal tendinous tissue as intralingual ligament appeared parallel and accompanied with skeletal muscle bundles and attached with entoglossal cartilage. It extended longitudinally from the root to the body of the egret's tongue. The salivary glands presented in the propria submucosal layer of the dorsal surface that extended laterally from apex to the root, while the ventral surface devoid from any glandular structures. The nature of lingual salivary glands showed variations in their histochemical observation to Alcian blue stain and PAS technique. It has been summarized that the morphological and histological variations of both tongues may be correlated to their feeding habits. [ABSTRACT FROM AUTHOR]