Gross Anatomical, Histological, and Scanning Electron Microscopic Characteristics of the Palate and Choanal Slit in the Budgerigar ( Melopsittacus undulatus )

Although the structures of the oropharyngeal roof have been described in several birds, there is a significant lack of detailed information on the anatomy of the palate and choanal slit in the Budgerigar. Accordingly, this study aimed to provide a comprehensive description of its palate, using gross anatomy, as well as light and scanning electron microscopy (SEM). The palate of the budgerigar consists of three parts: the fleshy, pre-choanal, and choanal parts. The fleshy part has a very small median palatine ridge between the two cushions, and this ridge diverges into two caudal lateral palatine ridges. The choanal part is divided into the rostral and caudal choanal regions. Interestingly, the infundibular slit is a small, elongated opening present in the middle of the choanal slit. Moreover, the SEM shows the presence of several openings of maxillary glands in the pre-choanal part. Histologically, the covering epithelium of the palate at the level of the choanal slit is stratified squamous epithelium, which at the edge of the choanal slit transforms into pseudostratified ciliated columnar epithelium with thick cilia, and is interrupted by mucous glands. In conclusion, the findings of the study have revealed that the budgerigar has distinct species-specific features.