Ramos colaterais dos arcos aórticos e suas principais ramificações em tartaruga (Trachemys scripta elegans)

Abstract

Background: Turtles (Trachemys scripta elegans) are exported to many countries with the purpose of being used as pets, however, despite commercial interest, there are few reports on their anatomy, based on this observation we proceeded on to conducting this study. Studies on the collateral branches of the aortic arch were found in domestic and wild species, however, there were few records regarding the turtle. This study aims to describe the collateral branches of the aortic arches and its major branches in the Trachemys scripta elegans, establishing a standard model and the main variations in this species. Materials, Methods & Results: After the Ethics Committee of Animal Use of the Federal University of Rio Grande do Sul approved the project, thirty turtles (Trachemys scripta elegans) were used, coming from the sorting centers of the Brazilian Institute of Environment and Natural Resources. The animals underwent preanesthetic medication administration, consisting of ketamine (80 mg/kg) and midazolam (2 mg/kg), administered intramuscularly in the forelimb. Euthanasia was performed one hour after the preanesthetic medication administration through an overdose of sodium thiopental (100 mg/kg) administered by the intracelomic route with subsequent use of vascular doppler for determination of death. The heart of each animal was accessed, the cardiac apex was sectioned for cannulation of the aortic arches through the single ventricle. The cranial cava veins were sectioned, the vascular system was rinsed with saline solution and filled with latex. The pieces remained immersed in water for polymerization of the latex, being stored in containers with formaldehyde. Subsequently, the arteries with its collateral branches were dissected. Schematic drawings were prepared for the elaboration of the results and the vessels were nominated. In all the samples studied, two atria and one ventricle were found, from which were originated two juxtaposed aortic arches, a right and a left one, at the base of the heart. From the beginning of the right aortic arch, a right and a left brachiocephalic trunk arose, each brachiocephalic trunk turning into a common carotid artery continuing on as subclavian artery to its respective antimere. The two aortic arches anastomosed forming the dorsal aorta. There was variation regarding the order of the branches arising from the left aortic arch, existing a predominance of the following: celiac artery, left gastric artery, anastomotic branch to the right aortic arch, continuing caudoventrally as cranial mesenteric artery. Discussion: The presence of two aortas in turtles is a fact reported in the literature and also observed in the present study. Regarding the origins and paths of right and left aortic arches, there is an agreement as to their origin; however, there is some discrepancy about the intersection of the arches after leaving the heart. Regarding the anastomotic branch, located between the right and left aortic arches, it was observed its presence in 100% of the samples, as described by different authors. It was found that the left aortic arch issued three branches, they being the celiac artery, the left gastric artery and the anastomotic branch to the right aortic arch, continuing on as cranial mesenteric artery, however controversies have been reported. It was observed variance regarding the order of the branches launched by the left aortic arch and some divergences about the distribution of the celiac artery. The cranial mesenteric artery was characterized as a vessel of great importance in this study, as a large portion of the viscera of the digestive tract are irrigated by it.