This research aimed to reveal the general morphology and topographic distribution of lingual papillae, epithelial characteristics, mucosal structure, and glands with their mucin content in the sheep tongue, with consideration of species-specific characteristics. The tongues of ten sheep were analyzed for this purpose. Filiform and fungiform papillae existed within the borders of the ventral surface of the lingual apex. The majority of the filiform papillae had multiple secondary projections. Fungiform papillae were also seen on the lingual torus among lenticular papillae, as well as 6 to 10 circumvallate papillae arranged on its caudal border. The species-specific details of the general anatomical structure of the tongue were determined and, in general, the papillary organization in the sheep was similar to goats, while the papillary organization also was similar to features with deer species, specifically the filiform papilla from the mechanical papillae and fungiform papilla from the gustatory papillae. Neutral and weak sulfated mucins and N-acetyl sialomucins were located in seromucous glands, salivary duct epithelium and von Ebner's glands. Carboxylated acid mucins and N-acetyl sialomucins were not present in seromucous and von Ebner's glands. In seromucous glands, MUC1, MUC5AC and MUC6 localized only in epithelial cells of ducts, whereas MUC2 localized in both glandular and ductal epithelial cells. All MUCs were present in both von Ebner's glands and salivary ducts. We showed that this mucin composition, may serve as a physical barrier in the initial section of the digestive system. This article is protected by copyright. All rights reserved.

1. The aim of the study was to examine the morphology of the tongue and the histochemical features of the lingual salivary glands in this species. 2. The tongue was elongated, terminating in a rather sharp, dagger-like apex. On the surface of the tongue and situated between the body and root of the tongue, two rows of conical papillae, the sharp apices of which pointed towards the posterior part of the tongue, were observed. The keratinised epithelium lining the dorsal surface lacked typical gustatory papillae. However, it was observed that taste buds were present in the epithelium of the lingual body and root. The tongue was supported by a structure composed of hyaline cartilage, the paraglossum, which extended from the lingual root to the apex. Simple branched tubular glands, which were encapsulated by connective tissue, were embedded within the submucosa in the body (anterior salivary glands) and root (posterior salivary glands) of the tongue. It was observed that the secretion of the lingual glands contained neutral mucins, proteoglycans containing carboxylic acid, weak and strong sulphated groups, N-acetylated sialomucins, but lacked glycogen. 3. It was demonstrated that, the general morphological features, papillary distribution of the tongue and the histological structure of the mucosa epithelium and the supportive elements displayed similarity to those of other domestic avian species. It was also determined that, in view of the particular feeding types, in the partridge, the presence of the papillary crest was not correlated with diet.

Morphology of the palatine mucosa and its secretion was described in Chukar partridges, by gross morphology and histochemistry techniques. For this purpose, 10 healthy adults (five male and five female) were sacrificed. After sacrifice, the palatine tissues were extirpated and fixed in 10% formol‐alcohol for 18 h and were embedded longitudinally and transversally in paraffin. The 5‐μm sections were employed histological and histochemical staining techniques. The lateral rims of the caudal part of the choanal cleft were bordered by large conical papillae. In the periphery of the choanal and the infundibular cleft, small papillae were scattered across the palatine mucosa. The palate was lined by keratinized stratified squamous epithelium, which contained conical papillae of varying height. However, the folds of the keratinized stratified squamous epithelial layer covering the choanal and infundibular cleft were nonkeratinized. The rostral aspect of the choanal cleft contained simple branched tubulo‐alveolar glands of both mucous and sero‐mucous characteristic, whilst the caudal aspect included mucous simple branched tubular glands. Furthermore, it was ascertained that the secretion of the palatine glands contained glycoproteins, carboxylated proteoglycans, weakly and strongly sulphated mucins, sialic acid and hyaluronic acid, but lacked glycogen. In conclusion, it was demonstrated that the histological structure of the mucosal epithelium and the supporting elements displayed similarity to those of other domestic avian species.

In the oesophagus, mucins, which originate from oesophageal submucosal glands, play an important role in the mucosal protection as a pre-epithelial barrier. In this study, the structure of cervical and thoracic parts of oesophagus of Japanese quail during the post-hatching period was compared, and the contents of carbohydrate and gastric mucin MUC5AC of the oesophageal glands in these parts were analysed at the light microscope levels by applying conventional histochemical and immunohistochemical methods. The oesophageal glands were present at hatching, located in the laminae propria. The numbers of glands were different in the cervical and thoracic parts, but the differences were found to be insignificant. The thoracic part has the oesophageal tonsils which are associated with the glands. Oesophageal tonsil was formed from day 5 after hatching. In quail of all ages, the secretory epithelium of glands contained neutral sialomucins and weakly sulphomucins. The cells in the neck region of secretory units contained sialomucins, while the cells of excretory ducts had strongly sulphomucins. Sialomucin containing cells in the secretory units increased with the advance of age and glandular development. But, in the secretory units, the sulphomucin content of glands was more in the thoracic part. The secretory epithelium of tonsil-associated glands contained mostly sulphomucins and a little sialomucin. From the hatching, MUC5AC mucin was detected in the cells of excretory ducts. Although the lymphoepithelium of the tonsil units exhibited negative reactions to all histochemical methods, it showed positive reaction to MUC5AC mucin antibody. In conclusion, the cervical and thoracic parts may be functionally different and the thoracic part of oesophagus was transformed into an immunological organ following day 5 after hatching.

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