EJMS

Abstract

Forty nine ducks ages from 1-60 days old, were used to demonstrate the post-hatching changes in the morphology of the tongue grossly, morphometrically and scanning electron microscopically. The tongue of the duck is characterized dorsally by presence of sulcus lingualis medianus, two pyramidal cushions and two transverse rows of conical caudally directed papillae between the body and root. Ventrally, it presents two elongated mucosal eminences. The length of the tongue measures about 20.64 mm at one day old, then increases one and half folds to become 32.80 mm at 15 days old to reach three folds (60.87 mm) at 60 days. The scanning electron microscopy at one day old, reveals that the median lingual groove is occupied by few low micro-longitudinal mucosal folds that carry cornified scales. These folds are increased in number, size and become more scaly with advancement of the age. The pyramidal cushions are demonstrated from the first day post- hatching. The dorsal surface of rostral projection of the cushions presents glandular openings and rosette- shaped papillae in older ducks. The caudal lingual papillae which are conical caudally directed papillae, have scaly wide base and pointed apices. These papillae are arranged in one transverse row at one day old and become arranged in two rows up to 15 days old. The length and width of ventral mucosal eminences depend on the age of post hatching ducks. According to current results we can conclude that the developmental changes in the duck tongue are important for the lingual adaptation to perform its role in the collecting and filtrating the eating food.