Abstract
The current work investigated the anatomical and histological structure of the tongue as well as the histochemical structures of the lingual salivary glands in the carnivore kingfisher (Halcyon smyrnensis) and the insectivore hoopoe (Upupa epops). The tongue is muscular elongated pointed organ, not bifid in both species, occupy about posterior third of the bill in kingfisher and about the posterior quarter of the bill in hoopoe. It is longer and bigger in kingfisher than in hoopoe and slightly more cylinder in hoopoe. Two of backwardly directed conical papillae in each side are found at the end of the tongue corpus of kingfisher. While in hoopoe a set of a double row of large conical papillae are located at the end of the lingual corpus and directed backwardly. Histologically, stratified keratinized epithelia in the dorsum of the tongue in kingfisher and non-keratinized in hoopoe were delineated; spine-like caudally directed lingual papillae are found in the posterior part of the dorsal lingual epithelium in kingfisher only. The tongue in both species contained muco-serous glands that are distributed in the corpus and radix, while the apex is devoid of glands. These lingual glands anteriorly are mostly of compound alveolar type and compound tubule- alveolar posteriorly. A few of taste buds were noticed only above the lingual glands at the radix of the tongue in both species. Histochemically; the lingual glands revealed both neutral and acidic nature of mucin secretion in both species, the acidic carbohydrate contents implies each of sialomucins and sulphomucins. The acidity of the lingual gland was mostly increased form the corpus toward the radix in both birds.