Meeting Abstract
P3.145 Thursday, Jan. 6 Vascular patterns in galliform birds: regions of thermal exchange PORTER, W.R.*; WITMER, L.M.; Ohio University; Ohio University wp298308@ohio.edu
The thermoregulatory ability of the avian head stems mainly from the rete mirabile ophthalmicum (RO), a vascular physiological device that functions to regulate the temperatures of the brain and eye somewhat independently from core body temperature. The venous blood cooled in the orbit, tongue, oral and nasal cavities via convective or evaporative cooling supports the function of the RO. Head vasculature was studied using multiple specimens of wild turkey and domestic pheasant to anatomically characterize structures supporting thermoregulation. Both species possess highly vascularized fleshy display structures. The importance of these fleshy structures in thermoregulation has some support, but our results indicate a role independent of the RO. Blood vessels were injected with a latex/barium solution of differing concentrations to discriminate arteries from veins in CT scans. Specimens were scanned using the OUµCT scanner at 90-micron slice thicknesses and analyzed using Amira/Avizo. Blood supply to the oral and nasal cavity was found to be extensive and derived from both the internal and external carotid arteries via the ventral nasal arteries. The venous drainage from the oral cavity receives the ophthalmic vein, which drains the RO, offering a potential pathway to the RO. The blood supply to the orbit is supplied from the internal carotid artery, although anastomoses with the external carotid artery via the facial artery were found. The venous drainage of the nasal cavity is though the ethmoid vein, which is also a tributary of the RO. Many anastomotic connections between the arteries of the orbit and the brain were found, offering a potential pathway for blood cooled in the RO to enter the cranial cavity. Comparing these taxa offers an insight into the extensive network of interconnected blood vessels that support thermoregulation.
