Anatomy of the Respiratory System of the African Grey Parrot (Psittacus erithacus)

Abstract

The morphology and function of the avian respiratory system has been studied and debated for over a century due to its distinct features, such as: unidirectional airflow, aerodynamic valves, and a volume‐constant lung ventilated by non‐vascularized, compliant air sacs. Intra‐ and interspecific variation in the shape, size, and number of avian bronchi and ventilatory air sacs has been described from gross dissections and latex injections, but little has been done to describe the three dimensional (3D) morphology and variation of the avian respiratory system in situ, largely due to the destructive nature of dissection. This research aims to generate a detailed anatomical description and 3D digital models of the lower respiratory system of the African grey parrot (Psittacus erithacus). Four micro‐computed tomography (micro CT) datasets of deceased P. erithacus specimens were segmented to produce 3D tetrahedral surface meshes of the pulmonary tree, lung surfaces, air sac surfaces, and skeleton. The anatomical models were then validated via latex injections. Bronchial tree measurements of P. erithacus (n=8) were collected for intraspecific and interspecific comparisons with two other well‐studied archosaurian taxa: the ostrich (Struthio camelus, n=10) and the American alligator (Alligator mississippiensis, n=10). Similarities in the relationships between the carina and the first four large secondary airways of the bronchial tree suggest a role in maintaining unidirectional airflow patterns in these taxa that would have been present in a common ancestor. In some P. erithacus specimens, the cervical air sacs were found to have a broad, thin, and sub‐sternal expansion that extended caudally to encapsulate more than half the ventral abdominal viscera. In another specimen, the right and left abdominal air sacs merged along the midline to form a single, common abdominal sac. These results suggest that the shape and extent of the air sacs in P. erithacus are more variable than previously described for other avian taxa. The models, which will be made available as a detailed 3D digital anatomical atlas through the Grey Parrot Anatomy Project, will likely become an invaluable resource to avian veterinarians for surgical planning.Support or Funding InformationAssociation of Avian Veterinarians (AAV) Research Grant AwardThis abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.