Light and scanning electron microscopic study of the tongue in the guinea fowl (Numida meleagris)

Abstract

Considering that, in birds, the tongue has an important role in taking food, so its shape and morphology are affected by the nutrition method and the environment of the animal. For this study, six adult female guinea fowl were prepared and, after slaughtering them humanely, their tongues were completely removed from the oral cavity and were completely washed with distilled water. After examining the morphology and measuring the tongue area, the tissue preparation stages were used for light and electron microscopes on each case. Morphological results showed that the tongue of the guinea fowl was triangular-shaped and the average length was 21.91 mm. The tongue consisted of three parts: apex, body, and root. The average length and width of apex were 8 and 6 mm, the average length and width of body were 6 mm and 8 mm, and the average root length and width were 7 and 9 mm, respectively. The examination of the tongue by a light microscope determined that the epithelium in the three parts of the tongue was keratinized stratified squamous, and the amount of keratinized on the ventral surface was more than on the dorsal surface. The connective tissue was of the dense irregular type and the salivary glands were observed in the root and body regions. The electron microscope results showed that the dorsal surface of the tongue contains filiform papillae which were more dense in the lateral edge than middle part of the tongue. A transverse row of giant conical papillae separated the body from the root of the tongue. In the ventral surface, from the root zone to the end region of the body, a concentric transverse fine eminence can be observed to be parallel to each other, and there was a ridge on the ventral surface along the length of the tongue, which has a reduction in its height from the root toward the apex. The glands’ openings were mostly located in the root region of the tongue, and the density was higher on the dorsal surface than on the ventral surface.