Scanning electron microscopic insights into the oropharyngeal cavity (tongue, laryngeal mound, and palate) of the Eurasian stone-curlew (Burhinus oedicnemus saharae): Anatomical adaptations to its feeding habits.

This study presents the first ultrastructural analysis of the Eurasian stone-curlew's oropharyngeal cavity through scanning electron microscopy (SEM) and gross anatomical observations, focusing on the tongue, laryngeal mound, and palate to understand structural adaptations related to feeding habits. The short tongue was divided into apex, body, and root, each exhibiting distinct anatomical and morphometric features. SEM showed the apex had a pointed nail, scales, and is bordered laterally by 2-3 membranes. The body is divided into a rostral papillary area and a caudal non-papillary area. The papillary system is restricted to the dorsal surface, especially on the apex and the rostral part of the body. Within this papillary area, there are three distinct filiform papillae types: thick papillae at the apex, elongated, pointed papillae along the lateral margins of the body, and broad, scale-like papillae at the median body region, along with the conical papillae on the papillary crest. Meanwhile, the caudal body part and root were devoid of papillae, yet featured numerous rounded salivary gland openings. The papillary crest had 14 small, pointed papillae arranged symmetrically on each side, with two large papillae at their lateral edges, each dividing into three papillae. The laryngeal mound had a notable glottis and a W-shaped papillary arrangement. The palatine region consists of rostral, middle, and caudal parts, with 2, 8, and 1 ridge(s), respectively. The choana is divided into a papillary rostral part and a non-papillary caudal part. The infundibulum had a median opening with no papillae and multiple sphenopterygoid gland openings.