Morphometrical, histological, and scanning electron microscopic investigations on the hard palate of Rahmani sheep (Ovis aries).

Abstract

The present study investigated the hard palate of Rahmani sheep (Ovis aries). Samples from nine healthy adult male sheep were investigated using morphometrical, histological and scanning electron microscopic examination. Morphologically, the hard palate was elongated, narrow rostrally, and wide caudally. The incisive papilla was heart-shaped, flanked on both sides by a groove on which the nasopalatine duct opened. The palatine raphe was in the form of a groove that contained a ridge caudally. On both sides of the raphe, 13-15 pairs of palatine ridges were present and mainly occupying the narrow part. The wide part had a rough part that contains few ridges rostrally and a smooth part caudally. Histologically, the incisive papilla and palatine ridges were lined by a keratinized stratified squamous epithelium resting on a dense layer of lamina propria. The incisive papilla characterized by the presence of seromucoid salivary glands and hyaline cartilage fragments in the lamina propria. The salivary glands became abundant and well-developed in the wide part till the end of hard palate. All palatine salivary glands were Alcian blue-periodic acid-Schiff positive. By scanning electron microscopy, numerous gland openings were scattered on the surface of the palatine ridges. In conclusion, the hard palate of Rahmani sheep presented characteristic features, which may be related to the species differences, feeding behavior, and possible functional adaptations. This is the first study to report the presence of cartilaginous segments and salivary glands in the incisive papilla and provide detailed descriptions of the Rahmani sheep hard palate.