Gross Anatomical Features of the Gastrointestinal Tract (GIT) of Blue and Yellow Macaws (Ara ararauna) - Oral Cavity and Pharynx

Summary Morphological studies of the gastrointestinal tract (GIT) of blue and yellow macaws (Ara ararauna) are scarce. Therefore, this study aims to describe the macaw's oropharyngeal cavity in order to supply the deficiency of anatomical data and as part of a broad study of the GIT of these birds. Two male and one female adult blue and yellow macaws were anatomically dissected to expose the oropharynx. The macaw oropharynx was ‘V‐shaped’ and flattened laterally being composed of maxillary and mandibular rhamphotheca of the beak. The tongue, lingual frenulum and laryngeal mound (containing ‘spindle‐shaped’ glottis and prominent mucosal papillae) formed the floor of the oropharynx. The roof revealed two distinct regions separated by a ‘step‐like depression’, whereas in the floor, the mandibular rhamphotheca was separated from the oral cavity mucosa by a large vestibulum enclosing the lingual frenulum. The palate was hard without any signs of rugae nor palatine raphe. A smooth ridge extended caudally from the choana to the common opening of the Eustachian tubes. This study, in addition to confirming the basic features of the oropharynx previously described for birds in general, provided new, unreported morphological data, some of which may be important when studying nutrition and health of these birds.