Comparative histological and ultrastructural studies on the tongue of two avian species (Lonchura oryzivora and Upupa epops)

Avian tongue has a significant role in the feeding process. The current investigation was planned to study the histological and ultrastructural features of the tongue in two avians. Java sparrow (Lonchura oryzivora) and Hoopoe (Upupa epops).

Fourteen birds were used including seven Java sparrows and seven Hoopoes during the current investigation. Careful procedures were used in the dissection process of the two avian species. Their heads were separated and four tongue samples (from each species) were taken to fixed in 10% buffered formalin for histological observations.

Histologically, the lingual glands in Lonchura oryzivora were simple-branched acinar and compound acinar. Whereas, the lingual glands in Upupa epops were simple acinar and simple-branched acinar. Three tongue samples (from each species) were taken to fixed in 2.5% of glutaraldehyde for the ultrastructural observations. The SEM findings in both species showed main three parts of the tongue; apex (anterior part), corpus (middle part) and radix (posterior part). Lonchura oryzivora's tongue has an elongated dart form with anterior terminal curved pointy conical papillae. Mid-dorsal trench (Sulcus medianus) extended from the apex to the anterior region of the radix. While the tongue of Upupa epops was triangular form with a convex tip and it has a V-form papillary crest. The observed findings of the histological and ultrastructural dissimilarities of Java Sparrow and Hoopoe emphasized more insight into the feeding behaviors and adaptation of the two avians.