Functional morphological study on the tongue of the adult Egyptian geese (Alopochen egyptiacus).

Abstract

Background: The present investigation represents the first attempt to fully describe the morphology of the geese tongue. Tongue has an essential biological role in all vertebrates, it is considered a prehensive organ, as it is responsible for food collection, also aids in mastication and swallowing. Since the tongue morphology was varied among bird species linked to different reasons such as beak shape, environment, feeding habits and type of diet, that's why the purpose of this study was to investigate the morphology of the geese tongue in detail concerning its function.

Methodology: Eleven adult healthy Egyptian geese of both sexes were used in this study, the heads of these birds were collected, and the tongue processed for gross investigation, morphometrical analysis, light microscopy, and scanning electron microscopy.

Result: The morphology of geese's tongue was unique, had narrow elongated shape with round thin free apex, with ventral keratinized lingual nail and caudal torus linguae. The apex and body had two groups of different shaped and sized marginal lingual papillae. The rostral group was 9-10 narrow spaced small thin conical papillae with pointed apices on the lateral margin of the tongue apex. And the caudal group was 6-7 widely spaced large thorn like conical papillae, positioned on the lateral margin of the caudal portion of the lingual apex and the body. Geese's tongue supported with entoglossal bone that extended from apex tip to transverse row of papillae where articulate with basibranchial bone.

Conclusion: The collected data described that the geese tongue was elongated in shape, its dorsum covered with keratinized stratified squamous epithelium and had two groups of mechanical marginal papillae which were necessary for the herbivorous birds as geese, depended on grassing as feeding behavior. Besides keratinization is a sign of tongue modification protecting lingual tissue against hard food particles. Conducting morphological results about geese tongue offers guidance and insights for its adaptation function and the management of this bird species.