Arterial vascularization of the stomach, duodenum, pancreas, liver and spleen in myocastor coypus (nutria)

Background: Rodents are the largest group of mammals. The nutria is a middle-sized rodent, native to South America, raised for meet and fur. This study has the objective to systematize and describe the arterial vascularization of the stomach, duodenum, pancreas, liver and spleen of nutria (Myocastor coypus). Materials, Methods & Results: Thirty young and adult nutrias (15 females and 15 males) were used. Animals were administered 5000 IU heparin and after 30 min 20 mL of 12.5% sodium thiopental by intraperitoneal injection. Then, the thoracic cavity was ventrally opened, the thoracic aorta cannulated close to the diaphragm and the system was washed with saline solution. After, the system was fi lled with 603 latex colored in red and pieces were immersed in 20% formol for fi xation for seven days. The abdominal cavity opened at the ventral median line, the branches of the abdominal aorta artery were dissected and, after the section of the main arterial trunks (celiac, caudal and cranial mesenteric arteries), the digestive tract was removed, sectioning the esophagus and rectus. Schematic drawings of all pieces were prepared with the use of a magnifying glass. The stomach, duodenum, pancreas, liver and spleen of the nutrias were exclusively irrigated by branches of the celiac and the cranial mesenteric arteries, visceral collateral fi rst and second branches of the abdominal aorta, respectively. The celiac artery presented a trifurcation after a short path, which originated the left gastric, the lienal and the hepatic arteries in 83.3% of the pieces. But in 16.7% of the cases, the celiac artery emitted the left gastric and lineal arteries, with the hepatic artery being a collateral branch of the cranial mesenteric artery. The lienal artery in 96.7% of the cases, projected lateralwards and emitted, after a short trunk, the left gastroeiploic artery, then continued until the spleen as lineal artery. The caudal pancreaticoduodenal artery was a right branch of the cranial mesenteric artery in 96.7% of the cases, and in 3.3% was branch of the hepatic artery, originated from the cranial mesenteric artery. Discussion: In nutria, it was observed that the celiac artery was originated from the ventral surface of the abdominal aorta, immediately caudal to the aortic hiatus. It was also observed the formation of a common trunk between the celiac and the cranial mesenteric arteries, what was not found in the studied species or in the White-lipped peccary. In nutria, the celiac artery originated, more frequently, the left gastric, lineal and hepatic arteries, with the same trifurcation observed in the White-lipped peccary. Also, in the nutria, the left gastric artery went towards the small curvature of the stomach and emitted a cardiac branch before reaching it and from this branch also emitted some esophagic branches and a large number of branches distributed on the visceral and parietal surfaces of the stomach. In the nutria, the left gastric artery also emitted a similar vessel, which dorsally countered the esophagus to the left and distributed to the left sac of the stomach, besides some ramifi cations to the esophagus. In the rabbit, as well as in the nutria, the lineal artery presented a similar trajectory and ramifi cation, but in none of the samples it was observed that this artery or the left gastroepiploic artery reached the pyloric region. In the White-lipped peccary, the hepatic artery was emitted in a common trunk with the splenic or left gastric arteries, what was not observed in any of the pieces in nutria. The stomach, duodenum, pancreas, liver and spleen of the nutria are vascularized by branches emitted from the celiac and cranial mesenteric arteries.